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Keratin is a natural material that can be derived from the cortex of human hair. Our group had previously presented a method for the printed, sequential production of three-dimensional (3D) keratin scaffolds. Using a riboflavin–sodium persulfate–hydroquinone (initiator–catalyst–inhibitor) photosensitive solution, we produced 3D keratin-based constructs through ultraviolet crosslinking in a lithography-based 3D printer. In this study, we have used this bioink to produce a keratin-based construct that is capable of delivering small molecules, providing an environment conducive to healing of dermal burn wounds in vivo, and maintaining stability in customized packaging. We characterized the effects of manufacturing steps, such as lyophilization and gamma irradiation sterilization on the properties of 3D printed keratin scaffolds prepared for in vivo testing. Keratin hydrogels are viable for the uptake and release of contracture-inhibiting Halofuginone, a collagen synthesis inhibitor that has been shown to decrease collagen synthesis in fibrosis cases. This small-molecule delivery provides a mechanism to reduce scarring of severe burn wounds in vitro. In vivo data show that the Halofuginone-laden printed keratin is noninferior to other similar approaches reported in literature. This is indicative that the use of 3D printed keratin is not inhibiting the healing processes, and the inclusion of Halofuginone induces a more organized dermal healing after a burn; in other words, this treatment is slower but improves healing. These studies are indicative of the potential of Halofuginone-laden keratin dressings in dermal wound healing. We aim to keep increasing the complexity of the 3D printed constructs toward the production of complex scaffolds for the treatment and topographical reconstruction of severe burn wounds to the face. IMPACT STATEMENT: Keratin-based photosensitive bioink can be used to three-dimensionally (3D) print complex scaffolds for the topical treatment of dermal burn wounds. We have developed reproducible protocols that allow us to 3D print large volumes of keratin-based hydrogels, and we now have a better understanding of how 3D printed geometrical features, crosslinking properties, or mass are altered due to the manufacturing processes. The printed hydrogels improved healing parameters in vivo on a porcine thermal burn model, indicative of the potential of the scaffolds for the regeneration of complex dermal wounds. Overall, our approach elucidates on physiological and topographical 3D healing of burn wounds.

One of the promising approaches to facilitate healing and regenerative capacity includes the application of growth-factor-loaded biomaterials. Human platelet lysate (hPL) derived from platelet-rich plasma through a freeze-thaw process has been used as a growth factor rich therapeutic in many regenerative applications. To provide sustained local delivery of the hPL-derived growth factors such as epidermal growth factor (EGF), the hPL can be loaded into biomaterials that do not degrade rapidly in vivo. Keratin (KSO), a strong filamentous protein found in human hair, when formulated as a hydrogel, is shown to sustain the release of drugs and promote wound healing. In the current study, we created a KSO biomaterial that spontaneously forms a hydrogel when rehydrated with hPL that is capable of controlled and sustained release of pro-regenerative molecules. Our study demonstrates that the release of hPL is controlled by changing the KSO hydrogel and hPL-loading concentrations, with hPL loading concentrations having a greater effect in changing release profiles. In addition, the 15% KSO concentration proved to form a stable hydrogel, and supported cell proliferation over 3 days without cytotoxic effects in vitro. The hPL-loaded keratin hydrogels show promise in potential applications for wound healing with the sustained release of pro-regenerative growth factors with easy tailoring of hydrogel properties.

Ionizing radiation causes injury to the skin that produces a complex clinical presentation that is managed by various paradigms without clear standards. The situation is further complicated by the fact that clinicians and researchers often use different terms and billing codes to describe the spectrum of cutaneous injury. There is, however, general agreement between the two most commonly-used diagnostic scales, the Radiation Therapy Oncology Group and the Common Terminology Criteria for Adverse Events, and in their use to describe skin injury following radiation therapy. These scales are typically used by radiation oncologists to quantify radiation dermatitis, a component of the radiation-related disorders of the skin and subcutaneous tissue family of diagnoses. In rare cases, patients with severe injury may require treatment by wound care or burn specialists, in which case the disease is described as a “radiation burn” and coded as a burn or corrosion. Further compounding the issue, most US government agencies use the term Cutaneous Radiation Injury to indicate skin damage resulting from large, whole-body exposures. In contrast, the US Food and Drug Administration approves products for radiation dermatitis or “burns caused by radiation oncology procedures.” A review of the literature and comparison of clinical presentations shows that each of these terms represents a similar injury, and can be used interchangeably. Herein we provide a comparative review of the commonly used terminology for radiation-induced skin injury. Further, we recommend standardization across clinicians, providers, and researchers involved in the diagnosis, care, and investigation of radiation-induced skin injury. This will facilitate collaboration and broader inclusion criteria for grant-research and clinical trials and will assist in assessing therapeutic options particularly relevant to patient skin pigmentation response differences.

Background Toxic epidermal necrolysis (TEN) is a severe, life-threatening mucocutaneous reaction, causing widespread sloughing of skin and mucosal surfaces. Accurate and prompt diagnosis is essential for optimal management and subsequent outcome. In this study, frozen sections were used as a rapid examination for initial diagnosis of TEN, and the frozen section diagnoses were assessed compared with permanent sections. Methods One hundred patients of suspected TEN were referred to our burn unit, and 67 had sufficient clinical findings for frozen and permanent biopsies. The accuracy of frozen section relative to permanent section was evaluated by calculating diagnostic accuracy, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV). And McNemar’s tests were used to analyze the difference between the two methods. Results Fifty-two specimens were classified as TEN by frozen section, 51 of which were confirmed by permanent biopsy. The exception was diagnosed as bullous pemphigoid on permanent section. Fifteen specimens were read as negative for TEN on frozen slides but 4 were changed to positive by permanent biopsy. Overall, the diagnostic accuracy of frozen section was 92.5%, with sensitivity and specificity 92.7% and 91.7% respectively. The positive predictive value, or coherence of positive diagnosis between the two methods, was as high as 98.1%, and the negative predictive value was 73.3%. The p-value of McNemar’s tests was 0.375, indicating there was no significant difference between the two biopsy methods. Conclusion The data suggest that as a rapid histological assessment, frozen section is a reliable tool in the early diagnosis of TEN.

While cutaneous radiation injury (CRI) is generally referenced as a consequence of a nuclear attack, it can also be caused by less dangerous events such as the use of dirty bombs, industrial radiological accidents, or accidental overexposure of beta (β) particle or gamma (γ) radiation sources in medical procedures. Although the gross clinical consequences of these injuries have been well documented, relatively little is known about the molecular changes underlying the progression of pathology. Here we describe a porcine model of cutaneous radiation injury after skin was exposed to strontium-90 b particle at doses of 16-42 Gy and characterize the anatomical and molecular changes over 70 days. The results show that irradiated sites displayed dosedependent increases in erythema and moist desquamation that peaked between days 35 and 42. Dose-dependent histopathological changes were observed, with higher doses exhibiting increased inflammation and epidermal hyperplasia beyond day 35. Furthermore, immunohistochemistry showed that exposure to 37 Gy β-particle radiation decreased epidermal cell proliferation and desmosomal junction proteins at day 70, suggesting compromised epidermal integrity. Metabolomic analysis of biopsies revealed dose- and time-dependent changes as high as 252-fold in several metabolites not previously linked to CRI. These alterations were seen in pathways reflecting protein degradation, oxidative stress, eicosanoid production, collagen matrix remodeling, mitochondrial stress, cell membrane composition and vascular disruption. Taken together, these data show that exposure to high doses of β particle damaged the molecular processes underlying skin integrity to a greater extent and for a longer period of time than has been shown previously. These findings further understanding of radiation-induced skin injury and serve as a foundation for the development and testing of potential therapeutics to treat CRI.

Objective: Cutaneous wound infection can lead to impaired healing, multiple surgical procedures, and increased hospitalization time. We tested the effectiveness of keratin-based hydrogels (termed “keratose”) loaded with ciprofloxacin to inhibit infection and support healing when topically administered to porcine excision wounds infected with Pseudomonas aeruginosa. Approach: Using a porcine excisional wound model, 10 mm full-thickness wounds were inoculated with 106 colony-forming units of P. aeruginosa and treated on days 1 and 3 postinoculation with ciprofloxacin-loaded keratose hydrogels. Bacteria enumeration and wound healing were assessed on days 3, 7, and 11 postinjury. Results: Ciprofloxacin-loaded keratose hydrogels reduced the amount of P. aeruginosa in the wound bed by 99.9% compared with untreated wounds on days 3, 7, and 11 postinjury. Ciprofloxacin-loaded keratose hydrogels displayed decreased wound contraction and reepithelialization at day 7 postinjury. By day 11, wounds treated with ciprof...

Ideal material characteristics for tissue engineering or regenerative medicine approaches to volumetric muscle loss (VML) include the ability to deliver cells, growth factors, and molecules that support tissue formation from a system with a tunable degradation profile. Two different types of human hair-derived keratins were tested as options to fulfill these VML design requirements: (1) oxidatively extracted keratin (keratose) characterized by a lack of covalent crosslinking between cysteine residues, and (2) reductively extracted keratin (kerateine) characterized by disulfide crosslinks. Human skeletal muscle myoblasts cultured on coatings of both types of keratin had increased numbers of multinucleated cells compared to collagen or Matrigel(TM) and adhesion levels greater than collagen. Rheology showed elastic moduli from 10(2) to 10(5) Pa and viscous moduli from 10(1) to 10(4) Pa depending on gel concentration and keratin type. Kerateine and keratose showed differing rates of degradation due to the presence or absence of disulfide crosslinks, which likely contributed to observed differences in release profiles of several growth factors. In vivo testing in a subcutaneous mouse model showed that keratose hydrogels can be used to deliver mouse muscle progenitor cells and growth factors. Histological assessment showed minimal inflammatory responses and an increase in markers of muscle formation. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 864-879, 2016.

Wounds to the head, neck, and extremities have been estimated to account for ∼84% of reported combat injuries to military personnel. Volumetric muscle loss (VML), defined as skeletal muscle injuries in which tissue loss results in permanent functional impairment, is common among these injuries. The present standard of care entails the use of muscle flap transfers, which suffer from the need for additional surgery when using autografts or the risk of rejection when cadaveric grafts are used. Tissue engineering (TE) strategies for skeletal muscle repair have been investigated as a means to overcome current therapeutic limitations. In that regard, human hair-derived keratin (KN) biomaterials have been found to possess several favorable properties for use in TE applications and, as such, are a viable candidate for use in skeletal muscle repair. Herein, KN hydrogels with and without the addition of skeletal muscle progenitor cells (MPCs) and/or insulin-like growth factor 1 (IGF-1) and/or basic fibroblast growth factor (bFGF) were implanted in an established murine model of surgically induced VML injury to the latissimus dorsi (LD) muscle. Control treatments included surgery with no repair (NR) as well as implantation of bladder acellular matrix (BAM). In vitro muscle contraction force was evaluated at two months postsurgery through electrical stimulation of the explanted LD in an organ bath. Functional data indicated that implantation of KN+bFGF+IGF-1 (n = 8) enabled a greater recovery of contractile force than KN+bFGF (n = 8)***, KN+MPC (n = 8)**, KN+MPC+bFGF+IGF-1 (n = 8)**, BAM (n = 8)*, KN+IGF-1 (n = 8)*, KN+MPCs+bFGF (n = 9)*, or NR (n = 9)**, (*p

Absorbable collagen sponges (ACS) are used clinically as carriers of recombinant human bone morphogenetic protein 2 (rhBMP-2) to promote bone regeneration. ACS exhibit ectopic bone growth due to delivery of supraphysiological levels of rhBMP-2, which is particularly problematic in craniofacial bone injuries for both functional and esthetic reasons. We hypothesized that hydrogels from the reduced form of keratin proteins (kerateine) would serve as a suitable alternative to ACS carriers of rhBMP-2. The rationale for this hypothesis is that keratin biomaterials degrade slowly in vivo, have modifiable material properties, and have demonstrated capacity to deliver therapeutic agents. We investigated kerateine hydrogels and freeze-dried scaffolds as rhBMP-2 carriers in a critically-sized rat mandibular defect model. ACS, kerateine hydrogels, and kerateine scaffolds loaded with rhBMP-2 achieved bridging in animals by 8 weeks as indicated by micro-computed tomography. Kerateine scaffolds achieved statistically increased bone mineral density compared to ACS and kerateine hydrogels, with levels reaching those of native bone. Importantly, both kerateine hydrogels and kerateine scaffolds had significantly less ectopic bone growth than ACS sponges at both 8 and 16 weeks post-operatively. These studies demonstrate the suitability of keratins as rhBMP-2 carriers due to equal regenerative capacity with reduced ectopic growth compared to ACS.

Drug coated balloons (DCB) represent a novel approach to develop a superior intervention for the treatment of peripheral artery disease (PAD). Currently, DCB are coated with anti-proliferative drugs which combat neointimal hyperplasia reducing the occurrence of restenosis. The common anti-proliferative drug is paclitaxel, which when coated alone has very poor retention rates due to its diffusion from the treated artery following deployment. Excipients have marginally improved paclitaxel retention however retention rates are still less than 10% 24-hours post-treatment. Keratose, an extracted form of keratin derived from human hair, is a potential option for an excipient due to its intrinsic scaffolding characteristics and biocompatibility. Keratose hydrogels support tunable release of various drugs and factors as a function of keratose concentration. Therefore, the goal of this project is to evaluate the ability of keratose to act as an excipient of paclitaxel in DCB. Briefly, various paclitaxel-containing keratose hydrogels were formed. Keratose degradation and paclitaxel release were quantified up to 45 days by spectrophotometry and HPLC-MS/MS respectively. To confirm the ability of keratose to form a DCB, keratose hydrogels were coated on angioplasty balloons using a dipping technique. The keratose DCB was sectioned and coating thickness was quantified by light microscopy. Results demonstrated that paclitaxel-keratose hydrogels degraded and released paclitaxel as a function of keratose concentration. The keratose DCB displayed uniform coating circumferentially with coating thicknesses ranging from 5-20 microns. These studies highlight the potential of a new biomaterial that can provide a safe and controllable drug release profile for treatment of PAD.

Please cite this paper as: Nunez, Trach, Burnett, Handa, Dyke, Callahan, and Smith (2011). Vasoactive Properties of Keratin-Derived Compounds. Microcirculation18(8), 663–669. Abstract Objective: Keratin proteins have been utilized as biomaterials for decades, and are currently under investigation for a variety of tissue regeneration and trauma applications. It has been suggested that certain keratins may have the capacity to act as a colloid in fluid resuscitation applications, providing viscosity and oncotic properties that may be beneficial during acute ischemic events. Oxidized keratin derivatives, also known as keratoses, show good blood and cardiovascular compatibility and thus are the subject of this study. Methods: The effects of keratose compounds will be assessed using a topload i.v. infusion model and observation of changes in the microvasculature of the cremaster muscle of rats. Results: Keratose resuscitation fluid (KRF) administration resulted in significant vasodilation in the cremaster muscle. This effect was blocked with pretreatment of l-NA to inhibit NO. Another keratin fraction, alpha-keratose, which is the primary viscosic compound, was not found to induce vasodilation. Conclusions: The apparent mechanism of vasodilation was found to be NO-mediated and isolated to a particular purified fraction, the KAP.

Caffeine is a commonly used neurostimulant that also produces cerebral vasoconstriction by antagonizing adenosine receptors. Chronic caffeine use results in an adaptation of the vascular adenosine receptor system presumably to compensate for the vasoconstrictive effects of caffeine. We investigated the effects of caffeine on cerebral blood flow (CBF) in increasing levels of chronic caffeine use. Low (mean = 45 mg/day), moderate (mean = 405 mg/day), and high (mean = 950 mg/day) caffeine users underwent quantitative perfusion magnetic resonance imaging on four separate occasions: twice in a caffeine abstinent state (abstained state) and twice in a caffeinated state following their normal caffeine use (native state). In each state, there were two drug conditions: participants received either caffeine (250 mg) or placebo. Gray matter CBF was tested with repeated-measures analysis of variance using caffeine use as a between-subjects factor, and correlational analyses were conducted between CBF and caffeine use. Caffeine reduced CBF by an average of 27% across both caffeine states. In the abstained placebo condition, moderate and high users had similarly greater CBF than low users; but in the native placebo condition, the high users had a trend towards less CBF than the low and moderate users. Our results suggest a limited ability of the cerebrovascular adenosine system to compensate for high amounts of daily caffeine use.

Keratin, a naturally-derived polymer derived from human hair, is physiologically biodegradable, provides adequate cell support, and can self-assemble or be crosslinked to form hydrogels. Nevertheless, it has had limited use in tissue engineering and has been mainly used as casted scaffolds for drug or growth factor delivery applications. Here, we present and assess a novel method for the printed, sequential production of 3D keratin scaffolds. Using a riboflavin-SPS-hydroquinone (initiator-catalyst-inhibitor) photosensitive solution we produced 3D keratin constructs via UV crosslinking in a lithography-based 3D printer. The hydrogels obtained have adequate printing resolution and result in compressive and dynamic mechanical properties, uptake and swelling capacities, cytotoxicity, and microstructural characteristics that are comparable or superior to those of casted keratin scaffolds previously reported. The novel keratin-based printing resin and printing methodology presented have the potential to impact future research by providing an avenue to rapidly and reproducibly manufacture patient-specific hydrogels for tissue engineering and regenerative medicine applications.

Infection is a leading cause of morbidity and mortality in burn patients. Current therapies include silver-based creams and dressings, which display limited antimicrobial effectiveness and impair healing. The need exists for a topical, point-of-injury antibiotic treatment that provides sustained antimicrobial activity without impeding wound repair. Fitting this description are keratin-based hydrogels, which are fully biocompatible and support the slow-release of antibiotics. Here we develop a porcine model of an infected partial-thickness burn to test the effects of ciprofloxacin-loaded keratin hydrogels on infection and wound healing. Partial-thickness burns were inoculated with either Pseudomonas aeruginosa or Methicillin-resistant Staphylococcus aureus, resulting in infections that persisted for >2 weeks that exceeded 10(5) and 10(6) cfu per gram of tissue, respectively. Compared to silver sulfadiazine, ciprofloxacin-loaded keratin hydrogel treatment significantly reduced the amount of P. aeruginosa and S. aureus in the burn by >99% on days 4, 7, 11, and 15 postinjury. Further, burns treated with ciprofloxacin-loaded keratin hydrogels exhibited similar healing patterns as uninfected burns with regards to reepithelialization, macrophage recruitment, and collagen deposition and remodeling. The ability of keratin hydrogels to deliver antibiotics to fight infection and support healing of partial-thickness burns make them a strong candidate as a first-line burn therapy.

Tunable erosion of polymeric materials is an important aspect of tissue engineering for reasons that include cell infiltration, controlled release of therapeutic agents, and ultimately to tissue healing. In general, the biological response to proteinaceous polymeric hydrogels is favorable (e.g., minimal inflammatory response). However, unlike synthetic polymers, achieving tunable erosion with natural materials is a challenge. Keratins are a class of intermediate filament proteins that can be obtained from several sources, including human hair, and have gained increasing levels of use in tissue engineering applications. An important characteristic of keratin proteins is the presence of a large number of cysteine residues. Two classes of keratins with different chemical properties can be obtained by varying the extraction techniques: (1) keratose by oxidative extraction and (2) kerateine by reductive extraction. Cysteine residues of keratose are "capped" by sulfonic acid and are unable to form covalent cross-links upon hydration, whereas cysteine residues of kerateine remain as sulfhydryl groups and spontaneously form covalent disulfide cross-links. Here, we describe a straightforward approach to fabricate keratin hydrogels with tunable rates of erosion by mixing keratose and kerateine. SEM imaging and mechanical testing of freeze-dried materials showed similar pore diameters and compressive moduli, respectively, for each keratose-kerateine mixture formulation (∼1200 kPa for freeze-dried materials and ∼1.5 kPa for hydrogels). However, the elastic modulus (G') determined by rheology varied in proportion with the keratose-kerateine ratios, as did the rate of hydrogel erosion and the release rate of thiol from the hydrogels. The variation in keratose-kerateine ratios also led to tunable control over release rates of recombinant human insulin-like growth factor 1.

Ideal material characteristics for tissue engineering or regenerative medicine approaches to volumetric muscle loss (VML) include the ability to deliver cells, growth factors, and molecules that support tissue formation from a system with a tunable degradation profile. Two different types of human hair-derived keratins were tested as options to fulfill these VML design requirements: (1) oxidatively extracted keratin (keratose) characterized by a lack of covalent crosslinking between cysteine residues, and (2) reductively extracted keratin (kerateine) characterized by disulfide crosslinks. Human skeletal muscle myoblasts cultured on coatings of both types of keratin had increased numbers of multinucleated cells compared to collagen or Matrigel(TM) and adhesion levels greater than collagen. Rheology showed elastic moduli from 10(2) to 10(5) Pa and viscous moduli from 10(1) to 10(4) Pa depending on gel concentration and keratin type. Kerateine and keratose showed differing rates of degradation due to the presence or absence of disulfide crosslinks, which likely contributed to observed differences in release profiles of several growth factors. In vivo testing in a subcutaneous mouse model showed that keratose hydrogels can be used to deliver mouse muscle progenitor cells and growth factors. Histological assessment showed minimal inflammatory responses and an increase in markers of muscle formation. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 864-879, 2016.

Traumatic injury is the leading cause of death in people aged 44 or less in the US. It is also estimated that 82% of deaths from battlefield hemorrhage may be survivable with better treatment options. In this study, two biomaterial hemostats having disparate mechanisms were evaluated in a large animal lethal hemorrhage model and compared to a commercial product and standard cotton gauze. We hypothesized that the biomaterial with a biologically active mechanism, as opposed to a mechanical mechanism, would be the most effective in this model. Using a published study protocol, the femoral artery in swine was punctured and treated. KeraStat™ (KeraNetics) and Nanosan®-Sorb (SNS Nano) hemostats were compared to a commercial chitosan dressing (second generation Hemcon®) and cotton gauze. Both KeraStat and Nanosan increased survival, significantly increased mean arterial pressure (MAP), and significantly decreased shock index compared to both controls. The Hemcon dressing was no different than gauze. Platelet adhesion assays suggested that the KeraStat mechanism of action involves β1 integrin mediated platelet adhesion while Nanosan-Sorb operates similar to one reported mechanism for Hemcon, absorbing fluid and concentrating clotting components. The Nanosan also swelled considerably and created pressure within the wound site even after direct pressure was removed.

Death after severe hemorrhage remains an important cause of mortality in people under 50 years of age. Keratin resuscitation fluid (KRF) is a novel resuscitation solution made from keratin protein that may restore cardiovascular stability. This postulate was tested in rats that were exsanguinated to 40% of their blood volume. Test groups received either low or high volume resuscitation with either KRF or lactated Ringer's solution. KRF low volume was more effective than LR in recovering cardiac function, blood pressure and blood chemistry. Furthermore, in contrast to LR-treated rats, KRF-treated rats exhibited vital signs that resembled normal controls at 1-week.

Driven by new discoveries in stem cell biology and regenerative medicine there is broad interest in biomaterials that go beyond basic interactions with cells and tissues to actively direct and sustain cellular behavior. Keratin biomaterials have the potential to achieve these goals but have been inadequately described in terms of composition structure and cell instructive characteristics. In this manuscript we describe and characterize a keratin based biomaterial demonstrate self assembly of cross linked hydrogels investigate a cell specific interaction that is dependent on the hydrogel structure and mediated by specific biomaterial receptor interactions and show one potential medical application that relies on receptor binding the ability to achieve hemostasis in a lethal liver injury model. Keratin biomaterials represent a significant advance in biotechnology as they combine the compatibility of natural materials with the chemical flexibility of synthetic materials. These characteristics allow for a system that can be formulated into several varieties of cell instructive biomaterials with potential uses in tissue engineering regenerative medicine drug and cell delivery and trauma. © 2012 Elsevier Ltd.

The present review illustrates the state of the art of regenerative medicine (RM) as applied to surgical diseases and demonstrates that this field has the potential to address some of the unmet needs in surgery. RM is a multidisciplinary field whose purpose is to regenerate in vivo or ex vivo human cells, tissues, or organs to restore or establish normal function through exploitation of the potential to regenerate, which is intrinsic to human cells, tissues, and organs. RM uses cells and/or specially designed biomaterials to reach its goals and RM-based therapies are already in use in several clinical trials in most fields of surgery. The main challenges for investigators are threefold: Creation of an appropriate microenvironment ex vivo that is able to sustain cell physiology and function in order to generate the desired cells or body parts; identification and appropriate manipulation of cells that have the potential to generate parenchymal, stromal and vascular components on demand, both in vivo and ex vivo; and production of smart materials that are able to drive cell fate. © 2012 by Lippincott Williams and Wilkins.

Keratin proteins have been utilized as biomaterials for decades, and are currently under investigation for a variety of tissue regeneration and trauma applications. It has been suggested that certain keratins may have the capacity to act as a colloid in fluid resuscitation applications, providing viscosity and oncotic properties that may be beneficial during acute ischemic events. Oxidized keratin derivatives, also known as keratoses, show good blood and cardiovascular compatibility and thus are the subject of this study.The effects of keratose compounds will be assessed using a topload i.v. infusion model and observation of changes in the microvasculature of the cremaster muscle of rats.Keratose resuscitation fluid (KRF) administration resulted in significant vasodilation in the cremaster muscle. This effect was blocked with pretreatment of l-NA to inhibit NO. Another keratin fraction, alpha-keratose, which is the primary viscosic compound, was not found to induce vasodilation.The apparent mechanism of vasodilation was found to be NO-mediated and isolated to a particular purified fraction, the KAP.

The superior colliculus (SC) plays an important role in integrating visual, auditory and somatosensory information, and in guiding the orientation of the eyes, ears and head. Previously we have shown that cats with unilateral SC lesions showed a preferential loss of multisensory orientation behaviors for stimuli contralateral to the lesion. Surprisingly, this behavioral loss was seen even under circumstances where the SC lesion was far from complete. To assess the physiological changes induced by these lesions, we employed single unit electrophysiological methods to record from individual neurons in both the intact and damaged SC following behavioral testing in two animals. In the damaged SC of these animals, multisensory neurons were preferentially reduced in incidence, comprising less than 25% of the sensory-responsive population (as compared with 49% on the control side). In those multisensory neurons that remained following the lesion, receptive fields were nearly twofold larger, and less than 25% showed normal patterns of multisensory integration, with those that did being found in areas outside of the lesion. These results strongly suggest that the multisensory behavioral deficits seen following SC lesions are the combined result of a loss of multisensory neurons and a loss of multisensory integration in those neurons that remain.

The general involvement of the superior colliculus (SC) in orientation behavior and the striking parallels between the multisensory responses of SC neurons and overt orientation behaviors have led to assumptions that these neural and behavioral changes are directly linked. However, deactivation of two areas of cortex which also contain multisensory neurons, the anterior ectosylvian sulcus and rostral lateral suprasylvian sulcus have been shown to eliminate multisensory orientation behaviors, suggesting that this behavior may not involve the SC. To determine whether the SC contributes to this behavior, cats were tested in a multisensory (i.e. visual-auditory) orientation task before and after excitotoxic lesions of the SC. For unilateral SC lesions, modality-specific (i.e. visual or auditory) orientation behaviors had returned to pre-lesion levels after several weeks of recovery. In contrast, the enhancements and depressions in behavior normally seen with multisensory stimuli were severely compromised in the contralesional hemifield. No recovery of these behaviors was observed within the 6 month testing period. Immunohistochemical labeling of the SC revealed a preferential loss of parvalbumin-immunoreactive pyramidal neurons in the intermediate layers, a presumptive multisensory population that targets premotor areas of the brainstem and spinal cord. These results highlight the importance of the SC for multisensory behaviors, and suggest that the multisensory orientation deficits produced by cortical lesions are a result of the loss of cortical influences on multisensory SC neurons.