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Immune checkpoint blockade antibodies have promising clinical applications but suffer from disadvantages such as severe toxicities and moderate patient–response rates. None of the current delivery strategies, including local administration aiming to avoid systemic toxicities, can sustainably supply drugs over the course of weeks; adjustment of drug dose, either to lower systemic toxicities or to augment therapeutic response, is not possible. Herein, we develop an implantable miniaturized device using electrode-embedded optical fibers with both local delivery and measurement capabilities over the course of a few weeks. The combination of local immune checkpoint blockade antibodies delivery via this device with photodynamic therapy elicits a sustained anti-tumor immunity in multiple tumor models. Our device uses tumor impedance measurement for timely presentation of treatment outcomes, and allows modifications to the delivered drugs and their concentrations, rendering this device potentially useful for on-demand delivery of potent immunotherapeutics without exacerbating toxicities., Immune checkpoint blockade antibodies have promising clinical applications, but suffer from severe toxicities and moderate response rates. Here the authors present an electrode-embedded, implantable optical fiber device with both local delivery and tumor impedance measurement capabilities to safely elicit durable anti-tumor immunity.

Breast cancer stem cells (BCSCs) are tumor initiating cells that can self-renew and are highly tumorigenic and chemoresistant. Therefore, the identification of factors critical for BCSC function is vital for the development of therapies. Here, we report that DNMT1-mediated FOXO3a promoter hypermethylation leads to downregulation of FOXO3a expression in breast cancer. FOXO3a is functionally related to the inhibition of FOXM1/SOX2 signaling and to the consequent suppression of BCSCs properties and tumorigenicity. Moreover, we found that SOX2 directly transactivates DNMT1 expression and thereby alters the methylation landscape, which in turn feedback inhibits FOXO3a expression. Inhibition of DNMT activity suppressed tumor growth via regulation of FOXO3a/FOXM1/SOX2 signaling in breast cancer. Clinically, we observed a significant inverse correlation between FOXO3a and FOXM1/SOX2/DNMT1 expression levels, and loss of FOXO3a expression or increased expression of FOXM1, SOX2, and DNMT1 predicted poor prognosis in breast cancer. Collectively, our findings suggest an important role of the DNMT1/FOXO3a/FOXM1/SOX2 pathway in regulating BCSCs properties, suggesting potential therapeutic targets for breast cancer.

Increasing evidence suggest that lncRNAs (long noncoding RNAs) play important roles in human cancer. Breast cancer is a heterogeneous disease and the potential involvement of lncRNAs in breast cancer remains unexplored. In this study, we characterized a novel lncRNA, RP1-5O6.5 (termed as RP1). We found that RP1 was highly expressed in breast cancer and predicted poor prognosis of breast cancer patients. Gain-of-function and loss-of-function assays showed that RP1 promoted the proliferation and metastasis of breast cancer cells in vitro and in vivo. Mechanistically, RP1 maintained the EMT and stemness states of breast cancer cells via repressing p27kip1 protein expression. RP1 combined with the complex p-4E-BP1/eIF4E to prevent eIF4E from interacting with eIF4G, therefore attenuating the translational efficiency of p27kip1 mRNA. Furthermore, we found that p27kip1 evidently downregulated Snail1 but not ZEB1 to inhibit invasion of breast cancer cells. Kruppel-like factor 5 (KLF5) was positively correlated with RP1 in breast cancer tissues. Moreover, we demonstrated that KLF5 recruited p300 to the RP1 promoter to enhance RP1 expression. Taken together, our findings demonstrated that KLF5-regulated RP1 plays an oncogenic role in breast cancer by suppressing p27kip1, providing support for the clinical investigation of therapeutic approaches focusing on RP1.

Resistance to Herceptin represents a significant challenge for successful treatment of HER2-positive breast cancer. Here, we show that in Herceptin-sensitive cells, FOXO3a regulates specific miRNAs to control IGF2 and IRS1 expression, retaining basic IGF2/IGF-1R/IRS1 signaling. The basic activity maintains expression of PPP3CB, a subunit of the serine/threonine-protein phosphatase 2B, to restrict FOXO3a phosphorylation (p-FOXO3a), inducing IGF2- and IRS1-targeting miRNAs. However, in Herceptin-resistant cells, p-FOXO3a levels are elevated due to transcriptional suppression of PPP3CB, disrupting the negative feedback inhibition loop formed by FOXO3a and the miRNAs, thereby upregulating IGF2 and IRS1. Moreover, we detect significantly increased IGF2 in blood and IRS1 in the tumors of breast cancer patients with poor response to Herceptin-containing regimens. Collectively, we demonstrate that the IGF2/IGF-1R/IRS1 signaling is aberrantly activated in Herceptin-resistant breast cancer via disruption of the FOXO3a-miRNA negative feedback inhibition. Such insights provide avenues to identify predictive biomarkers and effective strategies overcoming Herceptin resistance.

Metallic nano-optoelectrode arrays can simultaneously serve as nanoelectrodes to increase the electrochemical surface-to-volume ratio for high-performance electrical recording and optical nanoantennas to achieve nanoscale light concentrations for ultrasensitive optical sensing. However, it remains a challenge to integrate nano-optoelectrodes with a miniaturized multifunctional probing system for combined electrical recording and optical biosensing in vivo. Here, we report that flexible nano-optoelectrode-integrated multifunctional fiber probes can have hybrid optical-electrical sensing multimodalities, including optical refractive index sensing, surface-enhanced Raman spectroscopy, and electrophysiological recording. By physical vapor deposition of thin metal films through free-standing masks of nanohole arrays, we exploit a scalable nanofabrication process to create nano-optoelectrode arrays on the tips of flexible multifunctional fiber probes. We envision that the development of flexible nano-optoelectrode-integrated multifunctional fiber probes can open significant opportunities by allowing for multimodal monitoring of brain activities with combined capabilities for simultaneous electrical neural recording and optical biochemical sensing at the single-cell level.

Background MicroRNAs (miRNAs) show considerable promise as therapeutic agents to improve tumor treatment, as they have been revealed as crucial modulators in tumor progression. However, our understanding of their roles in gastric carcinoma (GC) metastasis is limited. Here, we aimed to identify novel miRNAs involved in GC metastasis and explored their regulatory mechanisms and therapeutic significance in GC. Methods The microRNA expression profiles of GC tumors at different stages and at different metastasis statuses were compared respectively using the stomach adenocarcinoma (STAD) miRNASeq dataset in TCGA. Using the above method, miR-4521 was picked out for further study. miR-4521 expression in GC tissues was examined by quantitative reverse transcription polymerase chain reaction (qRT-PCR) and in situ hybridization (ISH). Highly and lowly invasive cell sublines were established using a repetitive transwell assay. Gain-of-function and loss-of-function analyses were performed to investigate the functions of miR-4521 and its upstream and downstream regulatory mechanisms in vitro and in vivo. Moreover, we investigated the therapeutic role of miR-4521 in a mouse xenograft model. Results In this study, we found that miR-4521 expression was downregulated in GC tissues compared with adjacent normal tissues and that its downregulation was positively correlated with advanced clinical stage, metastasis status and poor patient prognosis. Functional experiments revealed that miR-4521 inhibited GC cell invasion and metastasis in vitro and in vivo. Further studies showed that hypoxia repressed miR-4521 expression via inducing ETS1 and miR-4521 mitigated hypoxia-mediated metastasis, while miR-4521 inactivated the AKT/GSK3β/Snai1 pathway by targeting IGF2 and FOXM1, thereby inhibiting the epithelial-mesenchymal transition (EMT) process and metastasis. In addition, we demonstrated that therapeutic delivery of synthetic miR-4521 suppressed gastric carcinoma progression in vivo. Conclusions Our results suggest an important role for miR-4521 in regulating GC metastasis and hypoxic response of tumor cells as well as the therapeutic significance of this miRNA in GC.

Understanding the cytoarchitecture and wiring of the brain requires improved methods to record and stimulate large groups of neurons with cellular specificity. This requires miniaturized neural interfaces that integrate into brain tissue without altering its properties. Existing neural interface technologies have been shown to provide high-resolution electrophysiological recording with high signal-to-noise ratio. However, with single implantation, the physical properties of these devices limit their access to one, small brain region. To overcome this limitation, we developed a platform that provides three-dimensional coverage of brain tissue through multisite multifunctional fiber-based neural probes guided in a helical scaffold. Chronic recordings from the spatially expandable fiber probes demonstrate the ability of these fiber probes capturing brain activities with a single-unit resolution for long observation times. Furthermore, using Thy1-ChR2-YFP mice we demonstrate the application of our probes in simultaneous recording and optical/chemical modulation of brain activities across distant regions. Similarly, varying electrographic brain activities from different brain regions were detected by our customizable probes in a mouse model of epilepsy, suggesting the potential of using these probes for the investigation of brain disorders such as epilepsy. Ultimately, this technique enables three-dimensional manipulation and mapping of brain activities across distant regions in the deep brain with minimal tissue damage, which can bring new insights for deciphering complex brain functions and dynamics in the near future., Existing neural interfaces are limited in accessing one, small brain region. Here, the authors introduce a scaffold with helix hollow channels, which direct multisite multifunctional fibre probes into the brain at different angles, allowing for simultaneous recording and stimulation across distant regions.

Metastasis remains the major obstacle to improved survival for breast cancer patients. Downregulation of FOXO3a transcription factor in breast cancer is causally associated with the development of metastasis through poorly understood mechanisms. Here, we report that FOXO3a is functionally related to the inhibition of VEGF-A/NRP1 signaling and to the consequent suppression of breast cancer metastasis. We show that FOXO3a directly induces miR-29b-2 and miR-338 expression. Ectopic expression of miR-29b-2/miR-338 significantly suppresses EMT, migration/invasion, and in vivo metastasis of breast cancer. Moreover, we demonstrate that miR-29b-2 directly targets VEGF-A while miR-338 directly targets NRP1, and show that regulation of miR-29b-2 and miR-338 mediates the ability of FOXO3a to suppress VEGF-A/NRP1 signaling and breast cancer metastasis. Clinically, our results show that the FOXO3a-miR-29b-2/miR-338-VEGF-A/NRP1 axis is dysregulated and plays a critical role in disease progression in breast cancer. Collectively, our findings propose that FOXO3a functions as a metastasis suppressor, and define a novel signaling axis of FOXO3a-miRNA-VEGF-A/NRP1 in breast cancer, which might be potential therapeutic targets for breast cancer.

Reduction of non-specific amplification and achievement of efficient amplification of multiple gene fragments under the same reaction condition is the basic goal of PCR diagnosis; however, this is often difficult. This study was conducted to establish a highly specific and effective amplification of the epidermal growth factor receptor (EGFR) gene's exons, 18-21, simultaneously.The 5'-tailed primers were synthesized by adding 10 to 20 bp of a non-specific sequence to the 5'-terminus of sequence-specific primers (tailless primers). The two-stage protocol consisted of 5-10 cycles of a conventional 3-step cycling, which was then followed by 30-35 cycles of two-step cycling. The exons 18-21 of EGFR gene were amplified in 28 non-small cell lung cancer (NSCLC) patients using an optimized PCR that combined 5' tailed primers with a two-stage protocol.The 5' tailed primers exhibited a wider range of suitable annealing temperatures, similar range of primer concentration, similar sensitivity, specificity, and reproducibility, as well as a reduced, non-specific amplification compared with the corresponding tailless primers. The amplification of exons 18-21 of EGFR gene in NSCLC patients revealed that a combination of 5' tailed primers with two-stage protocol (optimized PCR) had a similar PCR success rate (P = 0.873) but had significantly reduced non-specific amplification (P0.001) compared to conventional PCR.5' tailed primers exhibited a wider range of suitable annealing temperatures and improved specificity compared with conventional PCR primers. An optimized PCR was established with 5' tailed primers and a two-stage protocol to amplify exons 18-21 of the EGFR gene in NSCLC patients.

Increasing evidence suggests that therapy-induced senescence (TIS), a novel therapeutic approach in which low doses of therapeutic drugs or radiation are used to induce senescence, suppresses tumor development. Our previous in vitro studies have demonstrated that a low dose of metformin promoted hepatoma cell senescence instead of apoptosis via activation of AMP-activated protein kinase (AMPK) and inactivation of Sirtuin 1 (SIRT1) deacetylase activity. However, the intricate relationship between AMPK and SIRT1, and how they cooperate to induce senescence remains elusive. We showed here that persistent exposure to a low concentration of metformin led to AMPK activation in a mouse xenograft model of human hepatocellular carcinoma (HCC), resulting in senescence. Intriguingly, AMPK counter-regulated SIRT1 via direct phosphorylation in metformin-mediated senescence in hepatoma cells. Taken together, these findings suggest that a low dose of metformin could potentially be used as a TIS-inducing therapeutic drug for HCC, and that this occurs by inducing senescence of HCC cells via the AMPK-SIRT1 pathway.

DNA demethylases of the TET family function as tumor suppressors in various human cancers, but their pathogenic contributions and mechanisms of action in gastric carcinogenesis and progression remain unclear. Here, we report that TET is transcriptionally upregulated in gastric cancer, where it correlates with poor prognosis. Mechanistic investigations revealed that TET facilitated gastric carcinogenesis through a noncoding function of the 3′UTR, which interacted with miR-26. This interaction resulted in sequestration of miR-26 from its target EZH2, which released the suppression on EZH2, and thereby led to EZH2 overexpression in gastric cancer. Our findings uncover a novel noncoding function for TET family proteins in facilitating gastric carcinogenesis. Cancer Res; 77(22); 6069–82. ©2017 AACR.

Studies in several cancers have suggested that miR-218 has anti-tumor activities, but its function is yet to be elucidated. In this study, we investigated the regulation and function of miR-218 (miR-218-5p) in the cell cycle progression of gastric cancer (GC). We found that miR-218 could suppress proliferation of gastric cancer cells, induce cell cycle arrest at the G1 phase and inhibit tumor growth and metastasis in vivo. We also demonstrated that miR-218 specifically targeted the 3′-UTR regions of CDK6 and cyclin D1 and inhibited the expression of these molecules, which in turn repressed the pRb/E2F1 signaling pathway. Overexpression of CDK6 and Cyclin D1 reversed miR-218-mediated inhibition of pRB/E2F1 signaling and attenuated the miR-218-induced cell cycle arrest. More importantly, miR-218 expression was significantly reduced and inversely correlated with the levels of CDK6 and Cyclin D1 in gastric cancer tissues. Decreased miR-218 expression was also correlated with advanced clinical stage, lymph node metastasis, and poor prognosis in gastric cancer patients. Furthermore, we showed that miR-218 expression was directly activated by E2F1 through the transactivation of miR-218 host genes, SLIT2 and SLIT3, revealing a negative feedback regulation of miR-218 expression. Taken together, our results describe a regulatory loop miR-218-CDK6/CyclinD1-E2F1 whose disruption may contribute to cell cycle progression in gastric cancer and indicate the potential application of miR-218 in cancer therapy.

Optogenetic interrogation of neural pathways relies on delivery of light-sensitive opsins into tissue and subsequent optical illumination and electrical recording from the regions of interest. Despite the recent development of multifunctional neural probes, integration of these modalities within a single biocompatible platform remains a challenge. Here, we introduce a device composed of an optical waveguide, six electrodes, and two microfluidic channels produced via fiber drawing. Our probes facilitated injections of viral vectors carrying opsin genes, while providing collocated neural recording and optical stimulation. The miniature (< 200 μm) footprint and modest weight (

Electrical recording permits direct readout of neural activity but offers limited ability to correlate it to the network topography. On the other hand, optical imaging reveals the architecture of neural circuits, but relies on bulky optics and fluorescent reporters whose signals are attenuated by the brain tissue. Here we introduce implantable devices to record brain activities based on the field effect, which can be further extended with capability of label-free electrophysiological mapping. Such devices reply on light-addressable potentiometric sensors (LAPS) coupled to polymer fibers with integrated electrodes and optical waveguide bundles. The LAPS utilizes the field effect to convert electrophysiological activity into regional carrier redistribution, and the neural activity is read out in a spatially resolved manner as a photocurrent induced by a modulated light beam. Spatially resolved photocurrent recordings were achieved by illuminating different pixels within the fiber bundles. These devices were applied to record local field potentials in the mouse hippocampus. In conjunction with the raster-scanning via the single modulated beam, this technology may enable fast label-free imaging of neural activity in deep brain regions.

Long noncoding RNAs (lncRNA) have been observed in various cancer types. Our bioinformatic analysis of existing databases demonstrated overexpression of lncRNAThe overexpression ofWe demonstrated that lncRNAOur findings indicate that

Triple-negative breast cancer (TNBC) is very aggressive and currently has no specific therapeutic targets; as a consequence, TNBC exhibits poor clinical outcome. In this study, we showed that cancerous inhibitor of protein phosphatase 2A (Cip2a) represents a promising target in TNBC because Cip2a was highly expressed in TNBC cells and tumor tissues, and its expression showed an inverse correlation with overall survival in patients with TNBC. We found that inhibition of Cip2a in TNBC cells induced cell cycle arrest at the G2/M phase, inhibited cell proliferation and delayed tumor growth in the xenograft model. Moreover, Cip2a markedly decreased the expression and nuclear localization of p27Kip1 and this is critical for the ability of Cip2a to promote TNBC progression. Mechanistically, our studies showed that Cip2a promoted p27Kip1 phosphoration at Ser10 via inhibiting Akt-associated PP2A activity, which seems to relocalize p27Kip1 to the cytoplasm in TNBC cells. On the other hand, Cip2a also recruited c-myc to mediate the transcriptional inhibition of p27Kip1. Notably, we observed negative correlation between Cip2a and p27Kip1 expression in TNBC specimens. In addition, our data showed that Cip2a depletion could sensitize TNBC to PARP inhibition. Collectively, these data suggested that Cip2a effectively promotes TNBC cell cycle progression and tumor growth via regulation of PP2A/c-myc/p27Kip1 signaling, which could serve as a potential therapeutic target for TNBC patients.

In the present study, we demonstrated that the levels of DKK1 were decreased in serums and tissues of GC. DKK1 levels inversely correlated with tumor class, TNM stage, distant metastasis and lymph node metastasis of GC. GC patients with low DKK1 levels had a poor overall survival. DKK1 inhibited the proliferation of GC cells in vitro and in vivo. DKK1 also inhibited invasion, but enhanced chemo-sensitivity of GC cells. Mechanically, miR-493 levels increased in GC and directly targeted and down-regulated DKK1 expression. In agreement, miR-493 promoted proliferation of GC cells in vitro and in vivo. MiR-493 also promoted invasion and chemo-resistance of GC cells. However, DKK1 overexpression reversed the effects of miR-493 on proliferation, invasion and chemo-sensitivity. Thus, our results provide new insight for the role of miR-493/DKK1 axis in GC.

3D bioprinting is an emerging biofabrication process for the production of adherent cell-based products, including engineered tissues and foods. While process innovations are rapidly occurring in the area of process monitoring, which can improve fundamental understanding of process-structure-property relations as well as product quality by closed-loop control techniques, in-line sensing of the bioink composition remains a challenge. Here, we report that hollow multifunctional fibers enable in-line impedimetric sensing of bioink composition and exhibit selectivity for real-time classification of cell type, viability, and state of differentiation during bioprinting. Continuous monitoring of the fiber impedance magnitude and phase angle response from 102 to 106 Hz during microextrusion 3D bioprinting enabled compositional and quality analysis of alginate bioinks that contained fibroblasts, neurons, or mouse embryonic stem cells (mESCs). Fiber impedimetric responses associated with the bioinks that contained differentiated mESCs were consistent with differentiation marker expression characterized by immunocytochemistry. 3D bioprinting through hollow multifunctional fiber impedimetric sensors enabled classification of stem cells as stable or randomly differentiated populations. This work reports an advance in monitoring 3D bioprinting processes in terms of in-line sensor-based bioink compositional analysis using fiber technology and provides a non-invasive sensing platform for achieving future quality-controlled bioprinted tissues and injectable stem-cell therapies.

Breast cancer is the most frequently diagnosed tumor type and the primary leading cause of cancer deaths in women worldwide. Drug resistance is the major obstacle for breast cancer treatment improvement. TRAIL-inducing compound 10 (Tic10), a novel activator of FOXO3, exhibits potent antitumor efficacy both in vitro and in vivo. In the present study, we investigated the resistance reversal effect of Tic10 on multidrug-resistant breast cancer cells T47D/5Fu derived from T47D breast cancer cells. We found that FOXO3a was significantly decreased in T47D/5-Fu cells, whereas treatment of Tic10 enhances FOXO3a expression and nuclear translocation. Moreover, treatment of Tic10 could reverses 5-Fluorouracil resistance of T47D/5-Fu cells via induction of G0/G1 cell cycle arrest and apoptosis. Furthermore, we found that Tic10 decreased the expression of CDK4 via FOXO3a-dependment mechanism. In addition, our data showed that Tic10 could sensitize drug resistant T47D/5-Fu cells to 5-Fu in vivo. Taken together, these data suggested Tic10 as capable of restoring sensitivity for drug-resistant breast cancer cells.

Brain function depends on simultaneous electrical, chemical and mechanical signaling at the cellular level. This multiplicity has confounded efforts to simultaneously measure or modulate these diverse signals in vivo. Here we present fiber probes that allow for simultaneous optical stimulation, neural recording and drug delivery in behaving mice with high resolution. These fibers are fabricated from polymers by means of a thermal drawing process that allows for the integration of multiple materials and interrogation modalities into neural probes. Mechanical, electrical, optical and microfluidic measurements revealed high flexibility and functionality of the probes under bending deformation. Long-term in vivo recordings, optogenetic stimulation, drug perturbation and analysis of tissue response confirmed that our probes can form stable brain-machine interfaces for at least 2 months. We expect that our multifunctional fibers will permit more detailed manipulation and analysis of neural circuits deep in the brain of behaving animals than achievable before.

Purpose: Squamous cell carcinoma of tongue (SCCT) is the most common type of oral cavity carcinoma. Chemoresistance in SCCT is common, and the underlying mechanism remains largely unknown. We aimed to identify key molecules and signaling pathways mediating chemoresistance in SCCT. Experimental Design: Using a proteomic approach, we found that the HSP27 was a potential mediator for chemoresistance in SCCT cells. To further validate this role of HSP27, we performed various mechanistic studies using in vitro and in vivo models as well as serum and tissue samples from SCCT patients. Results: The HSP27 protein level was significantly increased in the multidrug-resistant SCCT cells and cell culture medium. Both HSP27 knockdown and anti-HSP27 antibody treatment reversed chemoresistance. Inversely, both HSP27 overexpression and recombinant human HSP27 protein treatment enhanced chemoresistance. Moreover, chemotherapy significantly induced HSP27 protein expression in both SCCT cells and their culture medium, as well as in tumor tissues and serum of SCCT patients. HSP27 overexpression predicts a poor outcome for SCCT patients receiving chemotherapy. Mechanically, extracellular HSP27 binds to TLR5 and then activates NF-κB signaling to maintain SCCT cell survival. TLR5 knockdown or restored IκBα protein level disrupts extracellular HSP27-induced NF-κB transactivation and chemoresistance. Moreover, intracellular HSP27 binds to BAX and BIM to repress their translocation to mitochondrion and subsequent cytochrome C release upon chemotherapy, resulting in inhibition of the mitochondrial apoptotic pathway. Conclusions: HSP27 plays a pivotal role in chemoresistance of SCCT cells via a synergistic extracellular and intracellular signaling. HSP27 may represent a potential biomarker and therapeutic target for precision SCCT treatment. Clin Cancer Res; 24(5); 1163–75. ©2017 AACR.

Development of resistance to therapy continues to be a serious clinical problem in lung cancer management. Cancer cells undergoing epithelial-to-mesenchymal transition (EMT) have been shown to play roles in resistance to chemotherapy. Here, we utilized a proteomics-based method and identified a significant downregulation of the metastasis suppressor NDRG1 in drug resistant lung cancer cells. We showed that downregulation of DNRG1 constitutes a mechanism for acquisition of EMT phenotype and endows lung cancer cells with an increased resistance to cisplatin. We also identified a signal cascade, namely, SET--| PP2A--| c-myc--| NDRG1, in which upregulation of SET is critical for inhibition of NDRG1. We also found that blockade of SET (or reactivation of PP2A) by FTY720 reverted EMT, restored drug sensitivity, and inhibited invasiveness and growth of lung tumor xenografts. Together, our results indicated a functional link between SET-mediated NDRG1 regulation and acquisition of EMT phenotype and drug resistance, and provided an evidence that blockade of SET-driven EMT can overcome drug resistance and inhibit tumor progression.

Synthetic neural scaffolds hold promise to eventually replace nerve autografts for tissue repair following peripheral nerve injury. Despite substantial evidence for the influence of scaffold geometry and dimensions on the rate of axonal growth, systematic evaluation of these parameters remains a challenge due to limitations in materials processing. We have employed fiber drawing to engineer a wide spectrum of polymer-based neural scaffolds with varied geometries and core sizes. Using isolated whole dorsal root ganglia as an in vitro model system we have identified key features enhancing nerve growth within these fiber scaffolds. Our approach enabled straightforward integration of microscopic topography at the scale of nerve fascicles within the scaffold cores, which led to accelerated Schwann cell migration, as well as neurite growth and alignment. Our findings indicate that fiber drawing provides a scalable and versatile strategy for producing nerve guidance channels capable of controlling direction and accelerating the rate of axonal growth. Keywords: Peripheral nerve repair; Neural scaffold; Fiber drawing; Tissue engineering, National Science Foundation (U.S.) (Award CBET-1253890), National Institute of Neurological Diseases and Stroke (U.S.) (Grant R01 NS086804-01A1)

Due to the limited regenerative ability of neural tissue, a diverse set of biochemical and biophysical cues for increasing nerve growth has been investigated, including neurotrophic factors, topography, and electrical stimulation. In this report, we explore optogenetic control of neurite growth as a cell-specific alternative to electrical stimulation. By investigating a broad range of optical stimulation parameters on dorsal root ganglia (DRGs) expressing channelrhodopsin 2 (ChR2), we identified conditions that enhance neurite outgrowth by three-fold as compared to unstimulated or wild-type (WT) controls. Furthermore, optogenetic stimulation of ChR2 expressing DRGs induces directional outgrowth in WT DRGs co-cultured within a 10 mm vicinity of the optically sensitive ganglia. This observed enhancement and polarization of neurite growth was accompanied by an increased expression of neural growth and brain derived neurotrophic factors (NGF, BDNF). This work highlights the potential for implementing optogenetics to drive nerve growth in specific cell populations., Charles Stark Draper Laboratory (University Research and Development Grant), National Science Foundation (U.S.). Materials Research Science and Engineering Centers (Program) (Award DMR-0819762), National Science Foundation (U.S.) (CAREER Award CBET-1253890), Simons Foundation, Korean Government Scholarship Program for Study Overseas