Search

Convection-enhanced delivery (CED) is a drug delivery technique used to deliver therapeutics directly to the brain and is a continually evolving technique to treat glioblastoma. Early versions of CED have proven to result in inadequate drug volume dispersed (Vd), increasing the likelihood of tumor recurrence. Fiber optic microneedle devices (FMDs) with the ability to deliver fluid and thermal energy simultaneously have shown an ability to increase Vd, but FMDs have historically had low light transmission efficiency. In this study, we present a new fabrication method, solid fiber inside capillary (SFIC) FMD, and a modified fusion splicing (FS) method with the goal of increasing light delivery efficiency. The modified FS FMD resulted in an increase in light transmission efficiency between 49% and 173% compared to previous prototypes. However, the FS FMD resulted in significantly lower transmission efficiencies compared to the SFIC FMD (p ≤ 0.04) and FS FMDs perform much worse when light-absorptive materials, like black dye, are placed in the bore. The light absorption of a candidate cytotoxic agent, QUAD-CTX, appear to be similar to water, and light delivery through FS FMDs filled with QUAD-CTX achieves a transmission efficiency of 85.6 ± 5.4%. The fabrication process of the SFIC FMDs results in extremely fragile FMDs. Therefore, the use of a modified FS FMD fabrication process appears to be better suited for balancing the desire to increase light transmission efficiency while retaining a sturdy FMD construction.

Convection-enhanced delivery (CED) is an investigational method for delivering therapeutics directly to the brain for the treatment of glioblastoma. However, it has not become a common clinical therapy due to an inability of CED treatments to deliver therapeutics in a large enough tissue volume to fully saturate the target region. We have recently shown that the combination of controlled catheter movement and constant pressure infusions can be used to significantly increase volume dispersed (V

The Convection-Enhanced Thermo-Therapy Catheter System (CETCS) was developed by our group at The University of Texas at Austin for the treatment of glioblastoma. This arborizing catheter is remotely operated and provides the ability to position and infuse in regions of the tumor and tumor margins to increase the dispersal volume coverage capability. The next step in developing this device is the further characterization of the materials being used in this design. Device characterization included evaluating the behavior of the microneedles under compression while they were in contact with several types of durometers (50A, 80A, 90A, and 95A). This test method was used to determine if the microneedles would experience breakage at the tip or along the microneedle. After the compression-durometer testing, it was determined the tips of the microneedles were more likely to puncture the durometer prior to experiencing any breakage. The device’s microneedles are not expected to come into contact with materials that have a higher durometer rating of 50A and will be acceptable in the current CETCS design meant for the treatment of glioblastomas.

Convection-enhanced delivery (CED) is an emerging method for treating highly aggressive and infiltrative forms of brain cancer, like glioblastomas. However, drawbacks of utilizing CED include limited availability of tools capable of bypassing the blood-brain barrier and blood-brain tumor barrier to deliver therapeutics to saturate the tumor and adjacent tumor periphery where highly infiltrative glioma cells may be located. The consequence is that tumor recurrence at or near the original tumor site is inevitable. The Convection-Enhanced Thermo-Therapy Catheter System (CETCS) is a remote-operable device comprising of an arborizing catheter and therapeutic delivery control system designed to maximize the distribution of therapeutics in target tissue volumes. In this study, we evaluate the performance of the CETCS in agarose gel brain tissue phantoms while monitoring the volume of infusate delivered, the dispersal volume of the infusate, and the mean distribution ratio of infusate. We report high infusion flow rates increase infusate dispersal volume but can result in backflow up the microneedles tracts; constant microneedle retraction maximizes infusate dispersal volume; and finally, low infusion flow rates resulted in better control of infusion cloud shape and minimized occurrence of backflow along microneedles.

Convection-enhanced delivery (CED) through an arborizing microneedle catheter system is an experimental drug delivery technique used to treat glioblastoma by providing a higher drug volume dispersed (Vd) of therapeutics directly to larger regions of brain tissue. A convection-enhanced thermo-chemotherapy catheter system (CETCS) can simultaneously deliver fluid and thermal energy to the infected area. The CETCS developed in our Medical Device Design lab comprises a bundle of 6 microneedles made from fiber optic capillary tubing, passed through a rigid cannula and individually arborized (branch-out). We are preparing CETCS for regulatory pathway application to advance it further toward clinical and human trials. In this paper, we performed three performance tests: infusion pressure, leakage, and constant pressure flow rate tests required by the FDA to file a traditional 510(K) based upon a potential predicate device. The high-pressure burst and leakage test showed that the CETCS can withstand an internal pressure of 100 psi with no leakage or failure in any connections and attachments, resulting in a substantial equivalency to the predicate devices. The constant pressure flow rate test showed a flow rate average of 0.64 ml/h under 0.7 psi and 1.69 ml/h under 2.1 psi of constant pressure using distilled water column, resulting in substantial equivalency to the predicate devices.

Convection-enhanced delivery (CED) has been extensively studied for drug delivery to the brain due to its inherent ability to bypass the blood-brain barrier. Unfortunately, CED has also been shown to inadequately distribute therapeutic agents over a large enough targeted tissue volume to be clinically beneficial. In this study, we explore the use of constant pressure infusions in addition to controlled catheter movement as a means to increase volume dispersed (Vd) in an agarose gel brain tissue phantom. Constant flow rate and constant pressure infusions were conducted with a stationary catheter, a catheter retracting at a rate of 0.25 mm/min, and a catheter retracting at a rate of 0.5 mm/min. The 0.25 mm/min and 0.5 mm/min retracting constant pressure catheters resulted in significantly larger Vd compared to any other group, with a 105% increase and a 155% increase compared to the stationary constant flow rate catheter, respectively. These same constant pressure retracting infusions resulted in a 42% and 45% increase in Vd compared to their constant flow rate counterparts. Using constant pressure infusions coupled with controlled catheter movement appears to have a beneficial effect on Vd in agarose gel. Furthermore, constant pressure infusions reveal the fundamental limitation of flow-driven infusions in both controlled catheter movement protocols as well as in stationary protocols where maximum infusion volume can never be reliably obtained.

The fiberoptic microneedle device (FMD) is a fused-silica microcatheter capable of co-delivery of fluids and light that has been developed for convection-enhanced delivery and photothermal treatments of glioblastoma. Here we investigate the biocompatibility of FMD fragments chronically implanted in the rat brain in the context of evaluating potential mechanical device failure. Fischer rats underwent craniectomy procedures for sham control (n & nbsp;= 16) or FMD implantation (n = 16) within the brain. Rats were examined daily after implantation, and at 14, 30, 90, and 180 days after implantation were evaluated via computed tomography of the head, hematologic and blood biochemical profiling, and necropsy examinations. Clinical signs of illness and distant implant migration were not observed, and blood analyses were not different between control and FMD implanted groups at any time. Mild inflammatory and astrogliotic reactions localized to the treatment sites within the brain were observed in all groups, more robust in FMD implanted groups compared to controls at days 30 and 90, and decreased in severity over days 90-180 of the study. One rat developed a chronic, superficial surgical site pyogranuloma attributed to the FMD silica implant. Chronically implanted FMD fragments were well tolerated clinically and resulted in anticipated mild, localized brain tissue responses that were comparable with other implanted biomaterials in the brain. National Institutes of Health/National Cancer Institute [P01CA207206] Published version Acknowledgements This study was funded by grant P01CA207206 from the National Institutes of Health/National Cancer Institute.

A common tool for diagnosis and treatment of gastrointestinal, gynecologic, and other anatomical pathologies is a form of minimally invasive surgery known as laparoscopy. Roughly 4 × 106 laparoscopic surgeries are performed in the U.S. every year, with an estimated 15 × 106 globally. During surgeries, lens clarity often becomes impaired via (1) condensation or (2) smearing of bodily fluids and tissues. The current gold standard solution requires scope removal from the body for cleaning, offering opportunity for decreased surgical safety and efficiency, while simultaneously generating mounting frustration for the operating room team. A novel lens cleaning device was designed and developed to clean a laparoscope lens in vivo during surgery. Benchtop experiments in a warm body simulated environment allowed quantification of lens cleaning efficacy for several lens contaminants. Image analysis techniques detected the differences between original (clean), postdebris, and postcleaning images. Mechanical testing was also executed to determine safety levels regarding potential misuse scenarios. Compared to gold standard device technologies, the novel lens cleaning device prototype showed strong performance and ability to clear a laparoscope lens of debris while mitigating the need for scope removal from the simulated surgical cavity. Mechanical testing results also suggest the design also holds inherently strong safety performance. Both objective metrics and subjective observation suggests the novel design holds promise to improve safety and efficiency during laparoscopic surgery.

Convection-Enhanced Delivery (CED) is an investigative treatment for brain tumors. Reflux has been shown to be a key issue in the success of CED treatments. Minimal research has been conducted to determine the onset of reflux. Furthermore, the ability to identify reflux allows for corrective action to be taken before the consequences of reflux renders the treatment unsuccessful. Reflux could be quickly identified by changes in pressure measured in the catheter. In this study we examine the difficulties associated with measuring inline pressure. Results indicate the measured inline pressure will change depending on catheter length and orientation. Therefore, relative changes in pressure coupled with early treatment imaging could be utilized to determine the success of CED treatment.

This paper presents an evaluation of the effect of needle geometry on the strength of a tether made using a barbed suture inserted into phantom tissue using a unique device. This tether is designed to secure an intrauterine device (IUD) to uterine fundus, with the aim of improving retention of IUDs inserted in the immediate postpartum period. A factorial experiment was designed to evaluate the effect of needle geometry on tether strength. Tether strength was characterized by the peak retention force of a suture subjected to a uniaxial tensile load. Experiments were performed using phantom tissue. Two needle geometries and three suture sizes were evaluated. Sutures deposited in phantom tissue with the helical needle had up to 132% increase in retention forces compared to sutures inserted with a straight needle, with more advantage at greater active length. The helical needle provides increased suture retention force and is a suitable tether delivery mechanism for this application.

Convection-enhanced delivery (CED) is an experimental method of localized treatment to release high concentrations of the drug into a target area. An implementation of CED by our lab is the convection-enhanced thermo-therapy catheter system (CETCS). The device is a collection of arborizing microneedles used to affect a broader coverage of a dispersed volume in the regions of interest. We suspect the coverage of the dispersal volume depends on the material properties of the brain the infusate is being administered. In this study, we create a computational model to evaluate how two adjacent materials with varying permeability (4.45 mm4 N-1 s-1 with 13.35 or 35.6 mm4 N-1 s-1) will disperse into a 0.6% (w/w) agarose gel. Transient state analysis was conducted using the FEBio Software Suite. As expected, results show a much larger dispersal volume in the material with the higher permeability and along the border of the two materials.

Standard treatment for glioblastoma is noncurative and only partially effective. Convection-enhanced delivery (CED) was developed as an alternative approach for effective loco-regional delivery of drugs via a small catheter inserted into the diseased brain. However, previous CED clinical trials revealed the need for improved catheters for controlled and satisfactory distribution of therapeutics. In this study, the arborizing catheter, consisting of six infusion ports, was compared to a reflux-preventing single-port catheter. Infusions of iohexol at a flow rate of 1 μL/min/microneedle were performed, using the arborizing catheter on one hemisphere and a single-port catheter on the contralateral hemisphere of excised pig brains. The volume dispersed (Vd) of the contrast agent was quantified for each catheter. Vd for the arborizing catheter was significantly higher than for the single-port catheter, 2235.8 ± 569.7 mm3 and 382.2 ± 243.0 mm3, respectively (n = 7). Minimal reflux was observed; however, high Vd values were achieved with the arborizing catheter. With simultaneous infusion using multiple ports of the arborizing catheter, high Vd was achieved at a low infusion rate. Thus, the arborizing catheter promises a highly desirable large volume of distribution of drugs delivered to the brain for the purpose of treating brain tumors.

The standard of care for treatment of glioblastoma results in a mean survival of only 12 to 15 months. Convection-enhanced delivery (CED) is an investigational therapy to treat glioblastoma that utilizes locoregional drug delivery via a small-caliber catheter placed into the brain parenchyma. Clinical trials have failed to reach their endpoints due to an inability of standard catheters to fully saturate the entire brain tumor and its margins. In this study, we examine the effects of controlled catheter movement on dye dispersal volume in agarose gel brain tissue phantoms. Four different catheter movement control protocols (stationary, continuous retraction, continuous insertion, and intermittent insertion) were applied for a single-port stepped catheter capable of intrainfusion movement. Infusions of indigo carmine dye into agarose gel brain tissue phantoms were conducted during the controlled catheter movement. The dispersal volume (Vd), forward dispersal volume (Vdf), infusion radius, backflow distance, and forward flow distance were quantified for each catheter movement protocol using optical images recorded throughout the experiment. Vd and Vdf for the retraction and intermittent insertion groups were significantly higher than the stationary group. The stationary group had a small but significantly larger infusion radius than either the retracting or the intermittent insertion groups. The stationary group had a greater backflow distance and lower forward flow distance than either the retraction or the intermittent insertion groups. Continuous retraction of catheters during CED treatments can result in larger Vd than traditional stationary catheters, which may be useful for improving the outcomes of CED treatment of glioblastoma. However, catheter design will be crucial in preventing backflow of infusate up the needle tract, which could significantly alter both the Vd and shape of the infusion.

The immediate post-partum period offers a convenient time to have an intrauterine device placed because of the co-location of a non-pregnant woman and her clinician; however, this practice is associated with increased expulsion rates of up to 30%, compared with a 3% expulsion rate for interval insertions. This paper presents a device and method to improve intrauterine device delivery and retention in the immediate postpartum period. This initial feasibility study illustrates that it is possible to temporarily tether a commercially available intrauterine device within the uterus of an immediately postpartum baboon. The results indicate this device and method are technically feasible, but further studies will be needed to evaluate safety and efficacy in reducing expulsion rates.

Clinical treatment of Glioblastoma Multiforme (GBM) is generally ineffective in increasing patient survival. Convection-enhanced delivery (CED) is an alternative, investigative therapy in which a small caliber catheter is placed directly into the brain parenchyma. However, standard CED drug delivery techniques are unable to reach the entirety of the brain tumor, attributing to the failure of Phase III clinical trials. Fiber optic microneedle devices (FMDs), capable of simultaneous fluid and laser energy delivery, have shown potential to increase the drug dispersal volume when compared to fluid only devices. Previously described FMDs have had low laser transmission efficiency. In this work, we present two FMD manufacturing methods, a solid fiber inside capillary (SFIC) FMD and a modified fusion spliced (FS) FMD. Transmission efficiency of the two proposed FMDs were measured using a 1064 nm laser and an integrating sphere detector with air, deionized water, and black ink inside of the bore of the FMDs. The transmission efficiency of the FS FMD was between 45 and 127% larger than that of previously reported FS FMDs. Additionally, the transmission efficiency of the SFIC was significantly higher than the FS FMD (p ≤ 0.04 for all groups). However, the SFIC FMDs suffered catastrophic fracture failure at bend radii smaller than the manufacture specification, likely due to scribing of the capillary during the FMD fabrication process. Modifying FS FMDs appears to be the preferred fabrication method providing improved light transmission efficiency and mechanical strength on par with the capillary manufacturer’s specifications.

Convection-enhanced delivery (CED) is an investigational therapy developed to circumvent the limitations of drug delivery to the brain. Catheters are used in CED to locally infuse therapeutic agents into brain tissue. CED has demonstrated clinical utility for treatment of malignant brain tumors; however, CED has been limited by lack of CED-specific catheters. Therefore, we developed a multiport, arborizing catheter to maximize drug distribution for CED. Using a multiphasic finite element (FE) framework, we parametrically determined the influence of design variables of the catheter on the dispersal volume of the infusion. We predicted dispersal volume of a solute infused in a permeable hyperelastic solid matrix, as a function of separation distance (ranging from 0.5 to 2.0 cm) of imbedded infusion cavities that represented individual ports in a multiport catheter. To validate the model, we compared FE solutions of pressure-controlled infusions to experimental data of indigo carmine dye infused in agarose tissue phantoms. The Tc50, defined as the infusion time required for the normalized solute concentration between two sources to equal 50% of the prescribed concentration, was determined for simulations with infusion pressures ranging from 1 to 4 kPa. In our validated model, we demonstrate that multiple ports increase dispersal volume with increasing port distance but are associated with a significant increase in infusion time. Tc50 increases approximately tenfold when doubling the port distance. Increasing the infusion flow rate (from 0.7 μL/min to 8.48 μL/min) can mitigate the increased infusion time. In conclusion, a compromise of port distance and flow rate could improve infusion duration and dispersal volume.

Glioblastoma has a 5 year survival of only 5.5% and a median patient survival of 12 to 15 months even with gold standard treatment. One potential method of improving treatment of glioblastoma is the use of convection-enhanced delivery (CED) which utilizes local delivery of therapeutics to the brain. However, clinical trials have shown an inability of standard catheters to deliver therapeutics to the entire target area. In this study, we explore the potential of controlled catheter movement to increase the volume dispersed (Vd) of indigo carmine dye in agarose gel brain tissue phantoms. We use four catheter control protocols: stationary, continuous retraction, continuous insertion, and intermittent insertion using a single port stepped catheter. The continuous retraction group resulted in consistent catheter clogging caused by the continued insertion of the catheter and therefore was removed from further analysis. Vd and backflow distance was quantified for all other catheter movement protocols using optical images captured throughout the infusion. Catheter retraction resulted in an increase in Vd of 51% while intermittent insertion resulted in a Vd increase of 24% compared to the stationary catheter. Additionally, a 37% reduction in backflow distance was seen with the retracting catheter when compared to the stationary catheter. These results are further supported by a simplified computational model that we have created. The computational model simulates the infusion of indigo carmine dye through an agarose gel brain tissue phantom and shows an increase in Vd of over 100% with catheter retraction. The increased Vd and decreased backflow distance afforded by the retracting catheter, suggests that the use of catheter movement may be a useful technique in increasing drug dispersal in tumorous tissue. Additional work in live and excised tissue should be conducted to confirm these results and an exploration of optimal needle movement protocols is necessary.

INTRODUCTION Annually, there are less than 20,000 cases of glioblastoma reported in the United States. This malignant tumor type has a survival rate of 5.6% and patient survival is approximately 14 months. The current standard of treatment is tumor resection, an attempt to remove the tumor; followed by, chemotherapy and radiation treatment. A newer form of treatment is convection-enhanced delivery (CED). Dr. Chris Rylander’s lab developed a novel method of CED, known as the convection-enhanced thermo-therapy catheter system (CETCS). The implementation of CETCS will be in an MRI environment, which calls for a need to improve the contrast of the needles against the native brain tissue. Increased contrast of the needles could improve remote control of the needles, and delivery of the drug. METHODS We evaluated several groups: (1) Control (water and air), (2) Nanomaterials in Polyimide Resin (Iron oxide nanoparticles and gadolinium oxide nanoparticles, some were contained in a polyetheretherketone tubing), and (3) Stainless Steel Wire (SS 316L). We cast needle groups into a 0.6% (w/w) Agarose phantom. Then, images were acquired with a 3T Siemens MRI and a 20-channel head coil in a series of 30 slices through the axial face of the phantom to the proximal face of the cube. Width analysis was conducted using Syngo FastView to determine the size of the artifacts in the MR images. RESULTS All modifications had a higher contrast than the controls, and the two largest artifacts measured were the SS 316L (4.9 ± 0.3 mm) and the iron oxide nanoparticles in the polyimide resin (3.5 ± 0.1 mm). An additional observation was the non-uniform shape of the two groups with the large artifacts. DISCUSSION Future iterations of these modifications need to be adjusted based on the desired artifact size, currently set to be at least 2 mm in diameter.

Convection-enhanced delivery (CED) is a promising technique leveraging pressure-driven flow to increase penetration of infused drugs into interstitial spaces. We have developed a fiberoptic microneedle device for inducing local sub-lethal hyperthermia to further improve CED drug distribution volumes, and this study seeks to quantitatively characterize this approach in agarose tissue phantoms. Infusions of dye were conducted in 0.6% (w/w) agarose tissue phantoms with isothermal conditions at 15 °C, 20 °C, 25 °C, and 30 °C. Infusion metrics were quantified using a custom shadowgraphy setup and image-processing algorithm. These data were used to build an empirical predictive temporal model of distribution volume as a function of phantom temperature. A second set of proof-of-concept experiments was conducted to evaluate a novel fiberoptic device capable of generating local photothermal heating during fluid infusion. The isothermal infusions showed a positive correlation between temperature and distribution volume, with the volume at 30 °C showing a 7-fold increase at 100 min over the 15 °C isothermal case. Infusions during photothermal heating (1064 nm at 500 mW) showed a similar effect with a 3.5-fold increase at 4 h over the control (0 mW). These results and analyses serve to provide insight into and characterization of heat-mediated enhancement of volumetric dispersal.

Near-infrared Spectroscopy (NIRS) is a broadly utilized technology with many emerging applications including clinical diagnostics, sports medicine, and functional neuroimaging, to name a few. For functional brain imaging NIR light is delivered at multiple wavelengths through the scalp and skull to the brain to enable spatial oximetry measurements. Dynamic changes in brain oxygenation are highly correlated with neural stimulation, activation, and function. Unfortunately, NIRS is currently limited by its low spatial resolution, shallow penetration depth, and, perhaps most importantly, signal corruption due to light interactions with superficial non-target tissues such as scalp and skull. In response to these issues, we have combined the non-invasive and rapidly reversible method of mechanical tissue optical clearing (MOC) with a commercially available NIRS system. MOC utilizes a compressive loading force on tissue, causing the lateral displacement of blood and water, while simultaneously thinning the tissue. A MOC-NIRS Breath Hold Test displayed a ∼3.5-fold decrease in the time-averaged standard deviation between channels, consequentially promoting greater channel agreement. A Skin Pinch Test was implemented to negate brain and muscle activity from affecting the recorded signal. These results displayed a 2.5-3.0 fold increase in raw signal amplitude. Existing NIRS instrumentation has been further integrated within a custom helmet device to provide a uniform force distribution across the NIRS sensor array. These results showed a gradual decrease in time-averaged standard deviation among channels with an increase in applied pressure. Through these experiments, and the development of the MOC-NIRS helmet device, MOC appears to provide enhancement of NIRS technology beyond its current limitations.

Convection-enhanced delivery (CED) is the process of local, pressure driven flow of drugs into brain parenchyma containing tumor tissue, resulting in greater distribution of the infused drugs compared to diffusion-dependent therapies. Nevertheless, even with the advantage of CED over simple diffusion, the large volumes necessary to target entire tumors and peritumor volumes have been previously unachievable with currently available catheters. We present a novel, multiport, arborizing catheter designed specifically for improving drug distribution into the brain. We evaluated the performance of the arborizing catheter by quantifying volume dispersed (Vd) and mean distribution ratios (Vd:Vi) in infusion studies using agarose brain phantoms and compared results to a single-port catheter. Three experimental groups were evaluated: (i) single-port infusions at 1 μL/min; (ii) single-port infusions at 7 μL/min; and (iii) seven-port arborizing catheter infusions at 1 μL/min/port. Significantly greater Vd was calculated for the arborizing catheter group (10.47 ± 1.07 cm3) compared with the single-port catheter groups at the low- and high-flow rates (2.36 ± 0.21 cm3 and 5.14 ± 0.56 cm3), respectively. Vd:Vi for the arborizing catheter was 37% lower than the single-port catheter at 1 μL/min, but 100% greater than the single-port catheter at 7 μL/min. The multiport, arborizing catheter produced the greatest distribution of the infusate, which would be advantageous for CED; however, it did not exhibit the greatest distribution ratio, likely due to overlapping distribution volumes from the multiple individual ports.

Background and Objectives: A fiberoptic microneedle device (FMD) was designed and fabricated for the purpose of enhancing the volumetric dispersal of macromolecules delivered to the brain through convection-enhanced delivery (CED) by concurrent delivery of sub-lethal photothermal hyperthermia. This study’s objective was to demonstrate enhanced dispersal of fluid tracer molecules through co-delivery of 1,064 nm laser energy in an in vivo rodent model. Materials and Methods: FMDs capable of co-delivering fluids and laser energy through a single light-guiding capillary tube were fabricated. FMDs were stereotactically inserted symmetrically into both cerebral hemispheres of 16 anesthetized rats to a depth of 1.5 mm. Laser irradiation (1,064 nm) at 0 (control), 100, and 200 mW was administered concurrently with CED infusions of liposomal rhodamine (LR) or gadolinium‐Evans blue-serum albumin conjugated complex (Gd‐EBA) at a flow rate of 0.1 ml/min for 1 hour. Line pressures were monitored during the infusions. Rodents were sacrificed immediately following infusion and their brains were harvested, frozen, and serially cryosectioned for histopathologic and volumetric analyses. Results: Analysis by ANOVA methods demonstrated that co-delivery enhanced volumetric dispersal significantly, with measured volumes of 15.8 � 0.6 mm 3 for 100 mW compared to 10.0 � 0.4 mm 3 for its fluid only control and 18.0 � 0.3 mm 3 for 200 mW compared to 10.3 � 0.7 mm 3 for its fluid only control. Brains treated with 200 mW co-delivery exhibited thermal lesions, while 100 mW co-deliveries were associated with preservation of brain cytoarchitecture. Conclusion: Both lethal and sub-lethal photothermal hyperthermia substantially increasethe rate of volumetric dispersal in a 1 hour CED infusion. This suggests that the FMD co-delivery method could reduce infusion times and the number of catheter insertions into the brain during CED procedures. Lasers Surg. Med. 2013 Wiley Periodicals, Inc.

Background and Objective Regenerative medicine involves the bioengineering of a functional tissue or organ by seeding living cells on a biodegradable scaffold cultured in a bioreactor. A major barrier to creating functional tissues, however, has been the inability to monitor the dynamic and complex process of scaffold maturation in real time, making control and optimization extremely difficult. Current methods to assess maturation of bioengineered constructs, such as histology or organ bath physiology, are sample-destructive. Optical coherence tomography (OCT) has recently emerged as a key modality for structural assessment of native blood vessels as well as engineered vessel mimics. The objective of this study was to monitor and assess in real time the development of a bioengineered blood vessel using a novel approach of combining both free-space and catheter-based OCT imaging in a new quartz-walled bioreactor. Development of the blood vessel was characterized by changes in thickness and scattering coefficient over a 30-day period. Materials and Methods We constructed a novel blood vessel bioreactor utilizing a rotating cylindrical quartz cuvette permitting free-space OCT imaging of an installed vessel's outer surface. A vascular endoscopic OCT catheter was used to image the lumen of the vessels. The quartz cuvette permits 360 degree, free-space OCT imaging of the blood vessel. Bioengineered blood vessels were fabricated using biodegradable polymers (15% PCL/collagen, ∼300 µm thick) and seeded with CH3 10t1/2 mesenchymal stem cells. A swept-source OCT imaging system comprised of a 20 kHz tunable laser (Santec HSL2000) with 1,300 nm central wavelength and 110 nm FWHM bandwidth was used to assess the vessels. OCT images were obtained at days 1, 4, 7, 14, 21, and 30. Free-space (exterior surface) OCT images were co-registered with endoscopic OCT images to determine the vessel wall thickness. DAPI-stained histological sections, acquired at same time point, were evaluated to quantify wall thickness and cellular infiltration. Non-linear curve fitting of free-space OCT data to the extended Huygen–Fresnel model was performed to determine optical scattering properties. Results Vessel wall thickness increased from 435 ± 15 µm to 610 ± 27 µm and Vessel scattering coefficient increased from 3.73 ±0.32 cm−1 to 5.74 ± 0.06 cm−1 over 30 days. Histological studies showed cell migration from the scaffold surface toward the lumen and cell proliferation over the same time course. The imaging procedure did not have any significant impact on scaffold dimensions, cell migration, or cell proliferation. Conclusions This study suggests that combination of free-space and catheter-based OCT for blood vessel imaging provides accurate structural information of the developing blood vessel. We determined that free-space OCT images could be co-registered with catheter-based OCT images to monitor structural features such as wall thickness or delamination of the developing tissue-engineered blood vessel within a bioreactor. Structural parameters and optical properties obtained from OCT imaging correlate with histological sections of the blood vessel and could potentially be used as markers to non-invasively and non-destructively assess regeneration of engineered tissues in real time. Lasers Surg. Med. 45:391–400, 2013. © 2013 Wiley Periodicals, Inc.

Background and Objectives Microneedles made from silica fiberoptics permit transmission and collection of light, which is an important functional advantage over metal or silicon microneedles. This added functionality may enhance or even enable new percutaneous light-based clinical diagnostic and therapeutic procedures. Micron-diameter fiberoptic microneedles, created from solid fibers capable of light emission and detection, are designed to penetrate several millimeters into tissue while minimizing tissue invasion and disruption. The mechanical strength (critical buckling force) of high aspect ratio (length to diameter) microneedles is a potential problem, which has motivated our invention of an elastomeric support device. In this study, we have tested our hypothesis that embedding the microneedles in an elastomeric support medium may increase microneedle critical buckling force. Materials and Methods The critical buckling force of silica microneedles with 55, 70, and 110 µm diameters and 3 mm lengths were measured with and without a surrounding elastomeric support (PDMS, polydimethylsiloxane). These experimental results were compared to theoretical calculations generated by the Rayleigh–Ritz buckling model. The insertion force required to penetrate ex vivo porcine skin was measured for microneedles with 55 and 70 µm diameters. Results Use of the PDMS support increased critical buckling force for microneedles of 55, 70, and 110 µm diameters by an average of 610%, 290%, and 33%, respectively. Theoretical calculations by the Rayleigh–Ritz model consistently overestimated the experimentally determined strengthening, but correlated highly with the greater enhancement offered to thinner microneedles. Aided by mechanical strengthening, microneedles 55 µm in diameter were able to repeatedly penetrate. Conclusions The critical buckling force of microneedles can be increased substantially to allow extremely high-aspect ratio microneedles, 55–110 µm in diameter and 3 mm in length, to penetrate ex vivo porcine skin. By this strengthening method, the safety and reliability of microneedles in potential clinical applications can be considerably enhanced. Lasers Surg. Med. 44: 421–428, 2012. © 2012 Wiley Periodicals, Inc.

Background and Objectives Mechanical indentation has been shown to increase light transmission through turbid tissue. In this study, we investigated the effects of localized indentation on the optical properties of ex vivo porcine skin specimens by dynamically monitoring diffuse reflectance spectra, light transmission, and applied load while controlling tissue thickness. Study Design/Methods A custom-built diffuse reflectance spectroscopy (DRS) system was used to capture diffuse reflectance spectra from tissue specimens undergoing indentation. The DRS probe was designed to perform both optical sensing and tissue indentation. A mechanical load frame was used to dynamically control probe displacement and resultant specimen thickness change while recording applied load. Diffuse reflectance spectra, as well as light transmission at 630 nm, were recorded during stress relaxation tests where tissue specimens were displaced to and held at a final thickness. Tissue optical properties were extracted from reflectance spectra using a previously established look-up table (LUT) approach. Results Indentation increased light transmission through tissue during linear displacement, and continued to increase transmission during subsequent stress relaxation at constant tissue thickness. The magnitude of relative transmission increases was shown to be a function of bulk tissue compressive strain (relative thickness change). Reduced scattering coefficients calculated from the LUT at 630 nm decreased during stress relaxation, with the relative decrease in scattering also depending strongly on tissue compressive strain. Reduced scattering coefficients decreased by 12.0 ± 4.7% at 0.44 ± 0.022 compressive strain, and reduced by 35.6 ± 1.3% at 0.71 ± 0.01 compressive strain. Conclusion DRS can be used to capture transient changes in intrinsic tissue optical properties during mechanical loading. Mechanical indentation modifies tissue optical properties and may be harnessed as a minimally-invasive optical clearing technique to improve optical diagnostics and therapeutics. Lasers Surg. Med. 44:303–309, 2012. © 2012 Wiley Periodicals, Inc.

Background and Objectives Photothermal therapies have limited efficacy and application due to the poor penetration depth of light inside tissue. In earlier work, we described the development of novel fiberoptic microneedles to provide a means to mechanically penetrate dermal tissue and deliver light directly into a localized target area. This paper presents an alternate fiberoptic microneedle design with the capability of delivering more diffuse, but therapeutically useful photothermal energy. Laser lipolysis is envisioned as a future clinical application for this design. Materials and Methods A novel fiberoptic microneedle was developed using hydrofluoric acid etching of optical fiber to permit diffuse optical delivery. Microneedles etched for 10, 30, and 50 minutes, and an optical fiber control were compared with three techniques. First, red light delivery from the microneedles was evaluated by imaging the reflectance of the light from a white paper. Second, spatial temperature distribution of the paper in response to near-IR light (1,064 nm, 1 W CW) was recorded using infrared thermography. Third, ex vivo adipose tissue response during 1,064 nm, (5 W CW) irradiation was recorded with bright field microscopy. Results Acid etching exposed a 3 mm length of the fiber core, allowing circumferential delivery of light along this length. Increasing etching time decreased microneedle diameter, resulting in increased uniformity of red and 1,064 nm light delivery along the microneedle axis. For equivalent total energy delivery, thinner microneedles reduced carbonization in the adipose tissue experiments. Conclusions We developed novel microscale optical diffusers that provided a more homogeneous light distribution from their surfaces, and compared performance to a flat-cleaved fiber, a device currently utilized in clinical practice. These fiberoptic microneedles can potentially enhance clinical laser procedures by providing direct delivery of diffuse light to target chromophores, while minimizing undesirable photothermal damage in adjacent, non-target tissue. Lasers Surg. Med. 43:914-920, 2011. © 2011 Wiley Periodicals, Inc.

Background and Objectives Mechanical tissue optical clearing permits light delivery deeper into turbid tissue, which may improve current optical diagnostics and laser-based therapeutic techniques. We investigated the effects of localized compression on brightfield imaging through ex vivo porcine skin by evaluating resolution and contrast of a target positioned beneath native, mechanically compressed, or chemically cleared specimens. We also evaluated the effects of indentation on dynamic tissue thickness and light transmission. Study Design/Methods A 5 mm diameter, hemispherically tipped, manual load transducer was used to compress specimens using 2–44 N for 60 seconds. Chemically cleared specimens were immersed for 1 hour in glycerol or dimethyl sulfoxide. A USAF 1951 resolution target was positioned beneath specimens and imaged using brightfield microscopy. Resolution and contrast of target features were analyzed. In separate experiments, a mechanical test instrument was used to compress and hold specimens at a final thickness while measuring applied load and light transmission. Results Image intensity profiles showed that while uncompressed skin did not allow resolution of any target, localized compression allowed maximum resolution (least line width) of 173 ± 21 µm. Mechanical clearing achieved up to four times higher maximum resolution and 2–3 times higher contrast sensitivity than chemical immersion. Resolving capability was highly correlated with compressive tissue strain. Light transmission increased during tissue compression, but also increased while holding final thickness constant. Conclusion Localized compression is an effective technique for increasing resolution and contrast of target features through tissue and may improve light-based diagnostics. Thickness reduction and other mechanisms appear to contribute to this effect. Lasers Surg. Med. 43: 814–823, 2011. © 2011 Wiley Periodicals, Inc.

Developing combinatorial treatments involving laser irradiation and nanoparticles require an understanding of the effect of nanoparticle inclusion on tissue thermal properties, such as thermal conductivity. This information will permit a more accurate prediction of temperature distribution and tumor response following therapy, as well as provide additional information to aid in the selection of the appropriate type and concentration of nanoparticles. This study measured the thermal conductivity of tissue representative phantoms containing varying types and concentrations of carbon nanotubes (CNTs). Multi-walled carbon nanotubes (MWNTs, length of 900–1200 nm and diameter of 40–60 nm), single-walled carbon nanotubes (SWNTs, length of 900–1200 nm and diameter

The highly disordered refractive index distribution in skin causes multiple scattering of incident light and limits optical imaging and therapeutic depth. We hypothesize that localized mechanical compression reduces scattering by expulsing unbound water from the dermal collagen matrix, increasing protein concentration and decreasing the number of index mismatch interfaces between tissue constituents. A swept-source optical coherence tomography (OCT) system was used to assess changes in thickness and group refractive index inex vivoporcine skin, as well as changes in signal intensity profile when imagingin vivohuman skin. Compression ofex vivoporcine skin resulted in an effective strain of −58.5%, an increase in refractive index from 1.39 to 1.50, and a decrease in water volume fraction from 0.66 to 0.20.In vivoOCT signal intensity increased by 1.5 dB at a depth of 1 mm, possibly due to transport of water away from the compressed regions. These finding suggest that local compression could be used to enhance light-based diagnostic and therapeutic techniques.

Nanoparticles have significant potential as selective photo-absorbing agents for laser based cancer treatment. This study investigates the use of single walled carbon nanohorns (SWNHs) as thermal enhancers when excited by near infrared (NIR) light for tumor cell destruction. Absorption spectra of SWNHs in deionized water at concentrations of 0, 0.01, 0.025, 0.05, 0.085, and 0.1 mg/ml were measured using a spectrophotometer for the wavelength range of 200-1,400 nm. Mass attenuation coefficients were calculated using spectrophotometer transmittance data. Cell culture media containing 0, 0.01, 0.085, and 0.333 mg/ml SWNHs was laser irradiated at 1,064 nm wavelength with an irradiance of 40 W/cm{sup 2} for 0-5 minutes. Temperature elevations of these solutions during laser irradiation were measured with a thermocouple 8 mm away from the incident laser beam. Cell viability of murine kidney cancer cells (RENCA) was measured 24 hours following laser treatment with the previously mentioned laser parameters alone or with SWNHs. Cell viability as a function of radial position was determined qualitatively using trypan blue staining and bright field microscopy for samples exposed to heating durations of 2 and 6 minutes alone or with 0.085 mg/ml SWNHs. A Beckman Coulter Vi-Cell instrument quantified cell viability of samples treated with varyingmore » SWNH concentration (0, 0.01, 0.085, and 0.333 mg/ml) and heating durations of 0-6 minutes. Spectrophotometer measurements indicated inclusion of SWNHs increased light absorption and attenuation across all wavelengths. Utilizing SWNHs with laser irradiation increased temperature elevation compared to laser heating alone. Greater absorption and higher temperature elevations were observed with increasing SWNH concentration. No inherent toxicity was observed with SWNH inclusion. A more rapid and substantial viability decline was observed over time in samples exposed to SWNHs with laser treatment compared with samples experiencing laser heating or SWNH treatment alone. Samples heated for 6 minutes with 0.085 mg/ml SWNHs demonstrated increasing viability as the radial distance from the incident laser beam increased. The significant increases in absorption, temperature elevation, and cell death with inclusion of SWNHs in laser therapy demonstrate the potential of their use as agents for enhancing photothermal tumor destruction.« less

This study demonstrates the capability of multiwalled carbon nanotubes (MWNTs) coupled with laser irradiation to enhance treatment of cancer cells through enhanced and more controlled thermal deposition, increased tumor injury, and diminished heat shock protein (HSP) expression. We also explored the potential promise of MWNTs as drug delivery agents by observing the degree of intracellular uptake of these nanoparticles. To determine the heat generation capability of MWNTs, the absorption spectra and temperature rise during heating were measured. Higher optical absorption was observed for MWNTs in water compared with water alone. For identical laser parameters, MWNT-containing samples produced a significantly greater temperature elevation compared to samples treated with laser alone. Human prostate cancer (PC3) and murine renal carcinoma (RENCA) cells were irradiated with a 1,064-nm laser with an irradiance of 15.3 W/cm2 for 2 heating durations (1.5 and 5 minutes) alone or in combination with MWNT inclusion. Cytotoxicity and HSP expression following laser heating was used to determine the efficacy of laser treatment alone or in combination with MWNTs. No toxicity was observed for MWNTs alone. Inclusion of MWNTs dramatically decreased cell viability and HSP expression when combined with laser irradiation. MWNT cell internalization was measured using fluorescence and transmission electron microscopy following incubation of MWNTs with cells. With increasing incubation duration, a greater number of MWNTs were observed in cellular vacuoles and nuclei. These findings offer an initial proof of concept for the application of MWNTs in cancer therapy. Cancer Res; 70(23); 9855–64. ©2010 AACR.

The complex morphological structure of tissue and associated variations in the indices of refraction of components therein, provides a highly scattering medium for visible and near-infrared wavelengths of light. Tissue optical clearing permits delivery of light deeper into tissue, potentially improving the capabilities of various light-based therapeutic techniques, such as adipose tissue removal or reshaping.We report results of a study to evaluate effectiveness of novel mechanical tissue optical clearing devices (TOCD) using white light photography and infrared imaging radiometry (IIR). The TOCD consists of a pin array and vacuum pressure source applied directly to the skin surface. IIR images recorded light absorption and temperature increase of ex vivo porcine skin and adipose during laser irradiation (980 and 1,210 nm) before and after TOCD application.White light photographic images of in vivo human skin demonstrated localized compression and altered visual appearance, indicative of water and blood movement in skin. White light photographic images also showed increased visible light transport through regions of ex vivo porcine skin compressed by TOCD pins. Rate of heating in sub-dermal adipose regions beneath TOCD pins was twofold higher following TOCD application.Results of our study suggest that mechanical optical clearing may provide a means to deliver increased light fluence to dermal and adipose tissues.

Biomedical Engineering Department, University of Texas of Austin, TexasBackground and Objectives: We describe a methodol-ogytorecordspatialvariation ofrefractiveindexofporcinerenal artery using differential phase optical coherencemicroscopy (DP-OCM).Study Design/Materials and Methods: The DP-OCMprovidesquantitativemeasurementofthinspecimenphaseretardationandrefractiveindexbymeasuringopticalpath-lengthchangesontheorderofafewnanometersandwithalateralresolutionof3mm.TheDP-OCMinstrumentationisan all-fiber, dual-channel Michelson interferometer con-structed using a polarization maintaining (PM) fiber.Results: Two-dimensional en face dual-channel phaseimages are taken over a 150 200 mm region on amicroscopic slide, and the images are reconstructed byplotting a two-dimensional refractive index map as theOCM beam is moved across the sample.Conclusions: Because the DP-OCM can record transientchangesintheopticalpath-length,thesystemmaybeusedto record quantitative optical path-length alterations oftissue in response to various stimuli. A fiber-based DP-OCM may have the potential to substantially improve invivo imaging of individual cells for a variety of clinicaldiagnostics, and monitoring applications. Lasers Surg.Med. 38:955–959, 2006. 2006 Wiley-Liss, Inc.Key words: phase sensitive optical coherence micro-scopy; refractive index; relative phase retardationINTRODUCTIONOptical coherence tomography (OCT) has emerged as animportantopticalimagingmodalityinnoninvasivemedicaldiagnostics. OCT generates high-resolution images byutilizing the cross correlation between light backscatteredfrom the sample and the reference reflector. Varioustechnical approaches have been developed to improveOCT spatial resolution, imaging acquisition rate [1,2],andimagequality[3,4].Mostofthesetechniquesusefringeamplitude or a combination of fringe amplitude andpolarization information in reflected light [5]. Magnitudeof back-reflected light is dependent on the local refractiveindex gradients of the structural components comprisingthe test specimen. Polarization information basicallyreveals different phase retardation, caused by a tissue,between two orthogonal polarization states of light.Knowledge of local refractive index variations in biologi-cal tissue is not only important in tissue optics but also amajor factor that determines fringe signal variation inconventionalOCT.Averagerefractiveindexoverrelativelyhomogeneous tissue medium has been measured byTearney et al.[6] and Knu¨ttel et al.[7]. The basic approachpresented by Tearney et al. [6] was to adjust the referencemirror for maximum signal at a particular focus positionwithinatissuewhereasKnu¨tteletal.[7]adaptedamovingfiber tip/collimating lens in the sample path in order totrace maximum signal variation. Two-dimensional bire-fringence mapping of porcine myocardium tissue wasreported [6]. The DP-OCM is capable of measuring opticalpath-length changes on the order of a few nanometers ( 5nm) [8] so that it can be applied to image two-dimensionallocal refractive index variation of thin specimens.This article presents a method to image refractive indexdistribution over a tissue specimen processed by standardhistology sectioning methods and fixated on a microscopeslide.MATERIALS AND METHODSDP-OCM Instrumentation and Signal ProcessingDetailsoftheDP-OCMusedforrefractiveindexprofilingcan be found in references [8,9]. A simplified schematicdiagram is shown in Figure 1. The DP-OCM system isessentially a dual-channel Michelson interferometer withtwo independent channels corresponding to orthogonalpolarization modes of a polarization maintaining (PM)optical fiber. At the interferometer input, light emittedfrom a broadband source (l

Lumen endothelialization of bioengineered vascular scaffolds is essential to maintain small-diameter graft patency and prevent thrombosis postimplantation. Unfortunately, nondestructive imaging methods to visualize this dynamic process are lacking, thus slowing development and clinical translation of these potential tissue-engineering approaches. To meet this need, a fluorescence imaging system utilizing a commercial optical coherence tomography (OCT) catheter was designed to visualize graft endothelialization.C7 DragonFly™ intravascular OCT catheter was used as a channel for delivery and collection of excitation and emission spectra. Poly-dl-lactide (PDLLA) electrospun scaffolds were seeded with endothelial cells (ECs). Seeded cells were exposed to Calcein AM before imaging, causing the living cells to emit green fluorescence in response to blue laser. By positioning the catheter tip precisely over a specimen using high-fidelity electromechanical components, small regions of the specimen were excited selectively. The resulting fluorescence intensities were mapped on a two-dimensional digital grid to generate spatial distribution of fluorophores at single-cell-level resolution. Fluorescence imaging of endothelialization on glass and PDLLA scaffolds was performed using the OCT catheter-based imaging system as well as with a commercial fluorescence microscope. Cell coverage area was calculated for both image sets for quantitative comparison of imaging techniques. Tubular PDLLA scaffolds were maintained in a bioreactor on seeding with ECs, and endothelialization was monitored over 5 days using the OCT catheter-based imaging system.No significant difference was observed in images obtained using our imaging system to those acquired with the fluorescence microscope. Cell area coverage calculated using the images yielded similar values. Nondestructive imaging of endothelialization on tubular scaffolds showed cell proliferation with cell coverage area increasing from 15 ± 4% to 89 ± 6% over 5 days.In this study, we showed the capability of an OCT catheter-based imaging system to obtain single-cell resolution and to quantify endothelialization in tubular electrospun scaffolds. We also compared the resulting images with traditional microscopy, showing high fidelity in image capability. This imaging system, used in conjunction with OCT, could potentially be a powerful tool for in vitro optimization of scaffold cellularization, ensuring long-term graft patency postimplantation.

The field of bioengineering is relatively new and complex including multiple disciplines encompassing areas in science and engineering. Efforts including the National Science Foundation (NSF) sponsored Integrative Graduate Education and Research Traineeship (IGERT) and VaNTH Engineering Research Center in Bioengineering Educational Technologies have been made to establish and disseminate knowledge and proven methods for teaching bioengineering concepts. Further, the summer bioengineering conference (SBC), sponsored by the American Society of Mechanical Engineers' (ASME) Bioengineering Division, was established to provide a meeting place for engineering educators and students having common interests in biological systems. Of the many subdisciplines of bioengineering, biotransport is a key subject that has wide applicability to many issues in engineering, biology, medicine, pharmacology, and environmental science, among others. The absence of standard content, guidelines, and texts needed for teaching biotransport courses to students motivated the Biotransport committee of ASME's Bioengineering Division to establish a biotransport education initiative. Biotransport education workshop sessions were conducted during the SBC 2011, 2012, and 2013 as part of this initiative. The workshop sessions included presentations from experienced faculty covering a spectrum of information from general descriptions of undergraduate biotransport courses to very detailed outlines of graduate courses to successful teaching techniques. A list of texts and references available for teaching biotransport courses at undergraduate and graduate levels has been collated and documented based on the workshop presentations. Further, based on individual teaching experiences and methodologies shared by the presenters, it was noted that active learning techniques, including cooperative and collaborative learning, can be useful for teaching undergraduate courses while problem based learning (PBL) can be a beneficial method for graduate courses. The outcomes of the education initiative will help produce students who are knowledgeable in the subject of biotransport, facile in applying biotransport concepts for solving problems in various application areas, and comfortable with their own abilities as life-long learners.

Single-walled carbon nanohorns (SWNHs) have significant potential for use in photothermal therapies due to their capability to absorb near infrared light and deposit heat. Additionally, their extensive relative surface area and volume makes them ideal drug delivery vehicles. Novel multimodal treatments are envisioned in which laser excitation can be utilized in combination with chemotherapeutic-SWNH conjugates to thermally enhance the therapeutic efficacy of the transported drug. Although mild hyperthermia (41–43 °C) has been shown to increase cellular uptake of drugs such as cisplatin (CDDP) leading to thermal enhancement, studies on the effects of hyperthermia on cisplatin loaded nanoparticles are currently limited. After using a carbodiimide chemical reaction to attach CDDP to the exterior surface of SWNHs and nitric acid to incorporate CDDP in the interior volume, we determined the effects of mild hyperthermia on the efficacy of the CDDP-SWNH conjugates. Rat bladder transitional carcinoma cells were exposed to free CDDP or one of two CDDP-SWNH conjugates in vitro at 37 °C and 42 °C with the half maximal inhibitory concentration (IC50) for each treatment. The in vitro results demonstrate that unlike free CDDP, CDDP-SWNH conjugates do not exhibit thermal enhancement at 42 °C. An increase in viability of 16% and 7% was measured when cells were exposed at 42 deg compared to 37 deg for the surface attached and volume loaded CDDP-SWNH conjugates, respectively. Flow cytometry and confocal microscopy showed a decreased uptake of CDDP-SWNH conjugates at 42 °C compared to 37 °C, revealing the importance of nanoparticle uptake on the CDDP-SWNH conjugate's efficacy, particularly when hyperthermia is used as an adjuvant, and demonstrates the effect of particle size on uptake during mild hyperthermia. The uptake and drug release studies elucidated the difference in viability seen in the drug efficacy studies at different temperatures. We speculate that the disparity in thermal enhancement efficacy observed for free drug compared to the drug SWNH conjugates is due to their intrinsic size differences and, therefore, their mode of cellular uptake: diffusion or endocytosis. These experiments indicate the importance of tuning properties of nanoparticle-drug conjugates to maximize cellular uptake to ensure thermal enhancement in nanoparticle mediated photothermal-chemotherapy treatments.

Single-walled carbon nanohorns (SWNHs) have great potential to enhance thermal and chemotherapeutic drug efficiencies for cancer therapies. Despite their diverse capabilities, minimal research has been conducted so far to study nanoparticle intracellular transport, which is an important step in designing efficient therapies. SWNHs, like many other carbon nanomaterials, do not have inherent fluorescence properties making intracellular transport information difficult to obtain. The goals of this project were to (1) develop a simple reaction scheme to decorate the exohedral surface of SWNHs with fluorescent quantum dots (QDs) and improve conjugate stability, and (2) evaluate SWNH–QD conjugate cellular uptake kinetics and localization in various cancer cell lines of differing origins and morphologies. In this study, SWNHs were conjugated to CdSe/ZnS core/shell QDs using a unique approach to carbodiimide chemistry. Transmission electron microscopy and electron dispersive spectroscopy verified the conjugation of SWNHs and QDs. Cellular uptake kinetics and efficiency were characterized in three malignant cell lines: U-87 MG (glioblastoma), MDA-MB-231 (breast cancer), and AY-27 (bladder transitional cell carcinoma) using flow cytometry. Cellular distribution was verified by confocal microscopy, and cytotoxicity was also evaluated using an alamarBlue assay. Results indicate that cellular uptake kinetics and efficiency are highly dependent on cell type, highlighting the significance of studying nanoparticle transport at the cellular level. Nanoparticle intracellular transport investigations may provide information to optimize treatment parameters (e.g., SWNH concentration, treatment time, etc.) depending on tumor etiology.

Biological tissues are heterogeneous materials that may be considered mixtures of water, proteins, and cells. The large mismatch in refractive index between these constituents causes tissues to be highly turbid, diffusing light and limiting the efficacy of optical diagnostic and therapeutic techniques [1]. Mechanical optical clearing is a technique for reducing tissue scattering and absorption using controlled tissue deformation. Mechanical optical clearing is performed using indentation to locally modify tissue optical properties, including refractive index [2] and reduced scattering coefficient [3]. This effect is attributed to transient changes in tissue water distribution as a result of interstitial fluid flow due to tissue compression. In this study, we have developed a multi-domain mathematical framework for simulating mechanical optical clearing effects on tissue mechanical and optical behavior, including hyperelasticity, viscoelasticity, porous flow, and light transport. This model was then fitted to mechanical force data and used to predict experimentally measured optical transmission.

A new image analysis method called the spatial phantom evaluation of cellular thermal response in layers (SPECTRL) is presented for assessing spatial viability response to nanoparticle enhanced photothermal therapy in tissue representative phantoms. Sodium alginate phantoms seeded with MDA-MB-231 breast cancer cells and single-walled nanohorns were laser irradiated with an ytterbium fiber laser at a wavelength of 1064 nm and irradiance of 3.8 W cm(-2) for 10-80 s. SPECTRL quantitatively assessed and correlated 3D viability with spatiotemporal temperature. Based on this analysis, kill and transition zones increased from 3.7 mm(3) and 13 mm(3) respectively to 44.5 mm(3) and 44.3 mm(3) as duration was increased from 10 to 80 s. SPECTRL provides a quantitative tool for measuring precise spatial treatment regions, providing information necessary to tailor therapy protocols.

A fiberoptic microneedle device (FMD) was designed and fabricated for the purpose of enhancing the volumetric dispersal of macromolecules delivered to the brain through convection-enhanced delivery (CED) by concurrent delivery of sub-lethal photothermal hyperthermia. This study's objective was to demonstrate enhanced dispersal of fluid tracer molecules through co-delivery of 1,064 nm laser energy in an in vivo rodent model.FMDs capable of co-delivering fluids and laser energy through a single light-guiding capillary tube were fabricated. FMDs were stereotactically inserted symmetrically into both cerebral hemispheres of 16 anesthetized rats to a depth of 1.5 mm. Laser irradiation (1,064 nm) at 0 (control), 100, and 200 mW was administered concurrently with CED infusions of liposomal rhodamine (LR) or gadolinium-Evans blue-serum albumin conjugated complex (Gd-EBA) at a flow rate of 0.1 µl/min for 1 hour. Line pressures were monitored during the infusions. Rodents were sacrificed immediately following infusion and their brains were harvested, frozen, and serially cryosectioned for histopathologic and volumetric analyses.Analysis by ANOVA methods demonstrated that co-delivery enhanced volumetric dispersal significantly, with measured volumes of 15.8 ± 0.6 mm(3) for 100 mW compared to 10.0 ± 0.4 mm(3) for its fluid only control and 18.0 ± 0.3 mm(3) for 200 mW compared to 10.3 ± 0.7 mm(3) for its fluid only control. Brains treated with 200 mW co-delivery exhibited thermal lesions, while 100 mW co-deliveries were associated with preservation of brain cytoarchitecture.Both lethal and sub-lethal photothermal hyperthermia substantially increase the rate of volumetric dispersal in a 1 hour CED infusion. This suggests that the FMD co-delivery method could reduce infusion times and the number of catheter insertions into the brain during CED procedures.

Regenerative medicine involves the bioengineering of a functional tissue or organ by seeding living cells on a biodegradable scaffold cultured in a bioreactor. A major barrier to creating functional tissues, however, has been the inability to monitor the dynamic and complex process of scaffold maturation in real time, making control and optimization extremely difficult. Current methods to assess maturation of bioengineered constructs, such as histology or organ bath physiology, are sample-destructive. Optical coherence tomography (OCT) has recently emerged as a key modality for structural assessment of native blood vessels as well as engineered vessel mimics. The objective of this study was to monitor and assess in real time the development of a bioengineered blood vessel using a novel approach of combining both free-space and catheter-based OCT imaging in a new quartz-walled bioreactor. Development of the blood vessel was characterized by changes in thickness and scattering coefficient over a 30-day period.We constructed a novel blood vessel bioreactor utilizing a rotating cylindrical quartz cuvette permitting free-space OCT imaging of an installed vessel's outer surface. A vascular endoscopic OCT catheter was used to image the lumen of the vessels. The quartz cuvette permits 360 degree, free-space OCT imaging of the blood vessel. Bioengineered blood vessels were fabricated using biodegradable polymers (15% PCL/collagen, ∼300 µm thick) and seeded with CH3 10t1/2 mesenchymal stem cells. A swept-source OCT imaging system comprised of a 20 kHz tunable laser (Santec HSL2000) with 1,300 nm central wavelength and 110 nm FWHM bandwidth was used to assess the vessels. OCT images were obtained at days 1, 4, 7, 14, 21, and 30. Free-space (exterior surface) OCT images were co-registered with endoscopic OCT images to determine the vessel wall thickness. DAPI-stained histological sections, acquired at same time point, were evaluated to quantify wall thickness and cellular infiltration. Non-linear curve fitting of free-space OCT data to the extended Huygen-Fresnel model was performed to determine optical scattering properties.Vessel wall thickness increased from 435 ± 15 µm to 610 ± 27 µm and Vessel scattering coefficient increased from 3.73 ± 0.32 cm⁻¹ to 5.74 ± 0.06 cm⁻¹ over 30 days. Histological studies showed cell migration from the scaffold surface toward the lumen and cell proliferation over the same time course. The imaging procedure did not have any significant impact on scaffold dimensions, cell migration, or cell proliferation.This study suggests that combination of free-space and catheter-based OCT for blood vessel imaging provides accurate structural information of the developing blood vessel. We determined that free-space OCT images could be co-registered with catheter-based OCT images to monitor structural features such as wall thickness or delamination of the developing tissue-engineered blood vessel within a bioreactor. Structural parameters and optical properties obtained from OCT imaging correlate with histological sections of the blood vessel and could potentially be used as markers to non-invasively and non-destructively assess regeneration of engineered tissues in real time.

Functional near-infrared spectroscopy (fNIRS) is a well-known technique for non-invasively measuring cerebral blood oxygenation, and many studies have demonstrated that fNIRS signals can be related to cognitive function. However, the fNIRS signal is attenuated by the skin, while scalp blood content has been reported to influence cerebral oxygenation measurements. Mechanical indentation has been shown to increase light transmission through soft tissues by causing interstitial water and blood flow away from the compressed region. To study the effects of indentation on fNIRS, a commercial fNIRS system with 16 emitter/detector pairs was used to measure cerebral blood oxygenation at 2 Hz. This device used diffuse reflectance at 730 nm and 850 nm to calculate deoxy- and oxy-hemoglobin concentrations. A borosilicate glass hemisphere was epoxied over each sensor to function as both an indenter and a lens. After placing the indenter/sensor assembly on the forehead, a pair of plastic bands was placed on top of the fNIRS headband and strapped to the head to provide uniform pressure and tightened to approx. 15 N per strap. Cerebral blood oxygenation was recorded during a breath holding regime (15 second hold, 15 second rest, 6 cycles) in 4 human subjects both with and without the indenter array. Results showed that indentation increased raw signal intensity by 85 ± 35%, and that indentation increased amplitude of hemoglobin changes during breath cycles by 313% ± 105%. These results suggest that indentation improves sensing of cerebral blood oxygenation, and may potentially enable sensing of deeper brain tissues.

This paper describes a new infusion catheter, based on our fiberoptic microneedle device (FMD), designed with the objective of photothermally augmenting the volumetric dispersal of infused therapeutics. We hypothesize that concurrent delivery of laser energy, causing mild localized photothermal heating (4-5 °C), will increase the spatial dispersal of infused chemotherapy over a long infusion period. Agarose brain phantoms, which mimic the brain’s mechanical and fluid conduction properties, were constructed from 0.6 wt% Agarose in aqueous solution. FMDs were fabricated by adhering a multimode fiberoptic to a silica capillary tube, such that their flat-polished tips co-terminated. Continuous-wave 1064 nm light was delivered simultaneously with FD&C Blue #2 (5%) dye into phantoms. Preliminary experiments, where co-delivery was tested against fluid delivery alone (through symmetrical infusions into in vivo rodent models), were also conducted. In the Agarose phantoms, volumetric dispersal was demonstrated to increase by more than 3-fold over a four-hour infusion time frame for co-delivery relative to infusion-only controls. Both forward and backward (reflux) infusions were also observed to increase slightly. Increased volumetric dispersal was demonstrated with co-delivery in an in vivo rodent model. Photothermal augmentation of infusion was demonstrated to influence the directionality and increase the volume of dye dispersal in Agarose brain phantoms. With further development, FMDs may enable a greater distribution of chemotherapeutic agents during CED therapy of brain tumors. Keywords: convection-enhanced delivery, fiberoptics, malignant glioma, simultaneous co-delivery, photothermal, minimally-invasive, chemotherapy, micorneedles