No description available.

Neurofibromatosis type 2 (NF2) is a benign tumor disease of the nervous system. Development of bilateral vestibular schwannomas is characteristic of NF2; however patients frequently present schwannomas on other nerves, as well as meningiomas and ependymomas. Currently, there are no drug therapies for NF2. There is an urgent need for development of NF2 therapeutics and this dissertation presents two independent potential therapeutic targets. The disease is caused by mutations in the NF2 gene that encodes a tumor suppressor called merlin. Loss of merlin function is associated with increased activity of Rac and p21-activated kinases (PAK) and deregulation of cytoskeletal organization. LIM domain kinases (LIMK1 and 2) are substrates for Cdc42/Rac-PAK, and modulate actin dynamics by phosphorylating cofilin, an actin severing and depolymerizing agent. LIMKs also translocate into the nucleus and regulate cell cycle progression. Here we report that mouse Schwann cells (MSCs) in which merlin function is lost as a result of Nf2 exon2 deletion (Nf2ΔEx2) exhibited increased levels of LIMK1, LIMK2, and active phospho-Thr508/505-LIMK1/2, as well as phospho-Ser3-cofilin, compared to wild-type normal MSCs. Similarly, levels of LIMK1 and 2 total protein and active phosphorylated forms were elevated in human vestibular schwannomas compared to normal human Schwann cells (SCs). Reintroduction of wild-type NF2 into Nf2ΔEx2 MSC reduced LIMK1 and LIMK2 levels. Pharmacological inhibition of LIMK with BMS-5, decreased the viability of Nf2ΔEx2 MSCs in a dose-dependent manner, but did not affect viability of iv control MSCs. Similarly, LIMK knockdown decreased viability of Nf2ΔEx2 MSCs. The decreased viability of Nf2ΔEx2 MSCs was due to inhibition of cell cycle progression as evidenced by accumulation of cells in G2/M phase. Inhibition of LIMKs arrest cells in early mitosis by decreasing Aurora A activation and cofilin phosphorylation. To increase the search for NF2 therapeutics, we applied an alternative approach to drug discovery with an unbiased pilot high-throughput screen of the Library of Pharmacologically Active Compounds. We assayed for compounds capable of reducing viability of Nf2ΔEx2 MSC as a cellular model for human NF2 schwannomas. AGK2, a SIRT2 (sirtuin 2) inhibitor, was identified as a candidate compound. SIRT2, a mammalian sirtuin, is a NAD+ -dependent protein deacetylase. We show that Nf2ΔEx2 MSC have higher expression levels of SIRT2 and lower levels of overall lysine acetylation than wild-type control MSC. Pharmacological inhibition of SIRT2 decreases Nf2ΔEx2 MSC viability in a dose dependent manner without substantially reducing wildtype MSC viability. Inhibition of SIRT2 activity in Nf2ΔEx2 MSC causes cell death accompanied by release of the necrotic markers lactate dehydrogenase and high mobility group box 1 protein into the medium in the absence of significant apoptosis, autophagy, or cell cycle arrest. Overall this work uncovered two novel potential therapeutic targets, LIMK and SIRT2 for NF2 and tumors associated with merlin deficiency.

No description available.

Keratins are a family of structural proteins that can be extracted from a variety of sources including wool, nails, skin, hooves, and hair. Keratin can be processed into different constructs such as coatings, scaffolds, and hydrogels, and has shown favorable results when placed in in vitro and in vivo settings for different tissue regeneration applications. Over three decades, keratin extraction technology has been continuously modified, and these differences in extraction processes have distinct effects on the characteristics of the end product. In this work, we examine the effect of keratin aggregation during a widely-used purification step, dialysis ultra-filtration, on material characteristics of the final keratin product when fabricated into a hydrogel. Two distinct dialysis procedures were applied during the extraction of oxidized keratin (keratose): one promoting protein aggregation and the other mitigating it. Analyses of material properties such as mechanical and enzymatic stability were conducted in addition to observing the differences in solution behavior between products. Data revealed that protein aggregation during the extraction process has a profound effect on keratose hydrogel material properties. After determination of the effect of protein aggregation during extraction on keratose hydrogels, investigation of how a blended material comprised of said keratose and type I collagen was undertaken. It was hypothesized that a blend would result in mixing at the molecular level, resulting in improved properties compared to either pure material alone. A protocol was created to make stable keratose/type I collagen blends and material characterization techniques were applied to determine the inherent properties of samples with differing ratios. Crosslinking density, mechanical properties, enzymatic degradation properties, water uptake capacity, structural architecture, and thermal properties were all assessed. In addition, the ability of this material to maintain cell viability was conducted. Results showed that the addition of type I collagen has a significant effect on the properties of hydrogel blends with keratose compared to the pure keratose system. This was mostly evident with hydrogel mechanical stability and material architecture. Finally, the ability to use this hybrid material as a luminal filler for a nerve conduit during peripheral nerve regeneration was explored in an in vitro setting. The ability of this blend to promote Schwann cell viability was assessed in addition to determining the ability of these cells to attach and migrate through the material matrix. These experiments demonstrate proof-of-concept for the application of using keratose/type I collagen matrices as a luminal filler in peripheral nerve guidance conduits. / Doctor of Philosophy / Keratins are a family of structural proteins that can be extracted from wool, skin, nails, and hair, and that have been investigated in the field of tissue regeneration. Humans make several types of keratins, so it has a natural acceptance by the body and its inflammatory and immune systems. However, keratins can be hard to make and process into useful products. Many methods for producing keratin biomaterials have been developed over the past 30 years, but most of them are not ideal. This work sought to explore a production method that addresses a particular problem, that of protein aggregation during purification. In so doing, methods can be optimized to create more useful keratin biomaterials. Experiments comparing preparation methods that maximize and minimize protein aggregation were compared. Data showed that minimizing aggregation leads to better biomaterial characteristics, thus demonstrating the potential impact of targeting this processing step. However, even after optimization of purification, keratins still have limitations. Most notably their mechanical strength is not as great as some other materials. A typical approach to address this in other systems has been by blending. In the present work, we explored a blend made from keratin and type 1 collagen. A method was developed to effectively blend keratin and collagen and create stable mixtures that yielded protein-to-protein coordination. Such interactions typically yield beneficial material characteristics such as increased strength. Data showed that intimate mixing of the two proteins was achieved, and resulting characteristics were improved compared to either pure material. Finally, studies were conducted to assess the potential for keratin/collagen blends to be used to regenerate injured nerves. A common method is to enclose the ends of a cut nerve into a tube and let the nerve re-grow through the tube to its target muscle. An important characteristic is an ability for cells to populate the interior of the tube and help the nerve fibers grow. In the present study, we investigated the behavior of a particularly important cell, the Schwann cell, to attach, move and grow through a keratin/collagen biomaterial. Data showed good cell behavior, suggesting that the material could be used in a medical product for nerve repair.

Cellular growth, development, differentiation, and death are mediated to some degree by the interaction of soluble factors with plasma membrane receptors. Traditionally the cellular response to chemical cues has been studied by exposing entire culture dishes to a desired reagent. While the addition of soluble reagents homogenously to cell culture dishes provides a basis for understanding much of cell biology, greater spatial resolution of reagent delivery is necessary in order to elucidate mechanisms on the subcellular scale. This dissertation explores techniques that may improve the quality and precision of delivering soluble factors to cultured cells in order to better understand the complex processes of cell biology. These advancements were made possible by applying high intensity, focused laser light to soluble materials to achieve microscopic three-dimensional (µ-3D) printing. In combination with a previously developed microfluidic cell dosing platform, microstructures were designed and µ-3D printed to hydrodynamically focus reagent streams for cell dosing. Structures were also µ-3D printed within micrometers of living cells from a solution of gelatin and bovine serum albumin with minimal cytotoxicity. When µ-3D printed, these proteins displayed both temperature and pH-responsive properties. In order to allow for on-the-fly control of reagent stream size and temporal pulse width, microstructures were µ-3D printed from temperature-responsive N- isoproplyacrylamide. To further improve the temporal resolution of the system, a technique for cycling between reagents with millisecond exchange times using laminar flow microfluidics was developed. The utility of these techniques was demonstrated by staining rat Schwann cells and mouse neuroblastoma rat glioma hybrid cells (NG108-15) with focused streams of fluorescent dyes. These advancements may allow future experiments to determine the placement of soluble factors necessary for bacterial quorum sensing or stem cell differentiation. / text

<p>Schwann cells (SCs) are PNS glia with numerous neuron-supporting functions, including myelination of axons. Although lesser discussed, SCs also fulfill many important roles after peripheral nerve injury (PNI) contributing significantly to the PNS regeneration process. Clusters of congregated SCs (Bands of Bungner) precede axon regeneration and facilitate the growth of extending axons to their distal targets which is particularly important in the lesion area of severed nerves. While this phenomenon occurs naturally, recovery from PNI can still be inadequate, especially in nerve transection or large gap injuries. Current treatments for nerve transection injuries are limited to coaptation of the nerve via sutures or nerve grafts. However, poor functional outcomes or donor site morbidity remain unaddressed problems. At the cellular level, axon pathfinding and extension relies heavily on the interaction between SCs and axonal growth cones. Depletion or removal of SCs at the lesion has been implicated to poor functional outcomes. With their pivotal role throughout nerve regeneration, we theorize axon regeneration can be improved by augmenting the SC population at the site of injury by encouraging migration to the lesion and via expression of morphological phenotypes that imitate the Bands of Bungner. </p> <p>DC electric fields (EFs) have been well studied in the past as a method to modulate cell orientation and migration and within the context of the nervous system, have been used to promote regeneration in lesioned spinal cords. However, very little work has investigated the effects of electrical stimulation on glia, such as SCs. Existing literature is lacking with regards to various aspects of SC responses, including direction of alignment. We hypothesize electrical stimulation can modulate SC behavior to reinforce/replicate behaviors observed within Bands of Bungner, which may be developed into a treatment for victims suffering peripheral nerve injury. </p> <p>We begin the current study with a thorough investigation into electric field modulated SC behavior. Using conventional 2D cell culture we demonstrate SC sensitivity to EFs by analyzing alignment, morphology and migration data. We employed EFs within the physiologic range. Waveforms used were constant DC as well as a 50% duty cycle DC and an oscillating DC. The latter two may prove more appropriate <i>in vivo</i> due to reduced accumulation of cytotoxic byproducts generated at the electrode interfaces. </p> <p>Our results highlight the sensitivity of SCs to DC electric fields of varying waveforms. SCs showed a strong propensity to align perpendicular to the field and display some cathodal migration in 2D cultures. Additional studies with variable cell density revealed cell-cell interaction further enhanced the alignment response. To more closely replicate the nerve microenvironment, a 3D cell culture model of PNI was created. Embedded in matrices, we found SCs displayed weaker migratory and alignment responses compared to 2D results. The direction of galvanotaxis was reversed, with SCs migrating toward the anode. Both alignment and migratory responses have potential applications for PNI. The galvanotactic behavior of SCs could be used to boost the SC population, increasing the number of Bands of Bungner. Cell alignment would be particularly advantageous at the lesion where axon regeneration is most difficult without the physical guidance of endoneurial tubes.</p> <p>This study characterizes SC behavior in applied EFs using conventional 2D and 3D cell culture techniques. We found SCs are sensitive to electric stimulation, supporting the idea that applied EFs could be used to indirectly promote regeneration in damaged peripheral nerve by modulating SC response after injury. Potential applications include generating an EF across damaged nerves to align SCs, especially in the lesioned area, using EFs to induce SC migration to the lesion to increase the number of cells guiding severed axons, and pre-aligning SCs in synthetic nerve grafts.</p>

Orientador: Maria Julia Marques / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-04T02:52:40Z (GMT). No. of bitstreams: 1 Pereira_ElaineCristinaLeite_D.pdf: 915105 bytes, checksum: 44cd1900344bb482d9d7f8badf08d53f (MD5) Previous issue date: 2005 / Resumo: Músculos distróficos apresentam alterações no complexo distrofinaglicoproteínas, bem como ausência da enzima óxido nítrico sintase neuronal, associada a alterações na estrutura da junção neuromuscular. No presente trabalho, estudamos as respostas dos terminais nervosos e das células de Schwann terminais após lesão nervosa, na ausência de óxido nítrico (NO). Nove dias após lesão nervosa por esmagamento, 24% das junções controle (n=200) apresentaram brotamentos ultraterminais. Na ausência de NO, o mesmo foi observado em 28.5% das junções (n=217; p>0.05 comparado aos controles; X2). Quatorze dias após a lesão nervosa, todas as células de Schwann terminais observadas formaram uma rede de processos citoplasmáticos, que se estendiam para fora do sítio sináptico. Em ausência do NO, as células de Schwann terminais não apresentaram processos fora da região juncional. Estes resultados mostram que o NO está envolvido na resposta das células de Schwann terminais à lesão nervosa. Isto sugere que a sinalização molecular entre os componentes présinápticos da junção neuromuscular pode estar prejudicada nos músculos distróficos, o que poderia influenciar a inervação e sobrevivência das novas fibras musculares obtidas por terapias celulares / Abstract: Dystrophic muscles show alterations in the dystrophinglycoprotein complex and a lack of neuronal nitric oxide (NO) synthase, associated with structural changes in neuromuscular junction. In this study, we examined the nerve terminal and Schwann cell responses after a crush lesion in NOdeficient mice. Nine days after nerve crush, 24% of the control junctions (n=200) showed ultraterminal sprouts. In the absence of NO, this frequency was 28.5% (n=217; p>0.05 compared to the controls; X2 test). Fourteen days after nerve lesion, all of the Schwann cells showed an extensive network of processes away from the synaptic site, whereas in the absence of NO, Schwann cells processes failed to extend away from the endplate. These results show that NO is involved in the Schwann cell response to nerve injury. They also suggest that presynaptic molecular signaling may be impaired in dystrophic muscles, and that this could influence the innervation and survival of newly formed myofibers generated by cellmediated therapies / Doutorado / Anatomia / Doutor em Biologia Celular e Estrutural

[ES] Las lesiones del sistema nervioso que implican la interrupción de haces axonales son devastadoras para el individuo. La regeneración autónoma de los tractos axonales dañados o degenerados es poco frecuente, ya que intervienen una gran cantidad de factores que limitan esta recuperación. Hoy en día, la medicina convencional no cuenta con tratamientos efectivos y exitosos para estas lesiones, y el tratamiento de los síntomas suele ser la mejor solución. Para revertirlo y lograr la reconexión funcional de las neuronas, la ingeniería de tejidos actualmente opta por el uso de soportes tridimensionales biocompatibles, células y moléculas bioactivas. Específicamente, una de las estrategias propuestas han sido los conductos nerviosos guiados, no solo para lesiones de nervios periféricos sino también para tractos del sistema nervioso central. En esta Tesis Doctoral, se propone la combinación de un conducto tubular hueco de ácido hialurónico (HA) relleno con fibras de ácido poli-L-lactida (PLA) en su lumen, y con células de Schwann (SC) pre-cultivadas como células de soporte de la extension axonal para superar los obstáculos que limitan la regeneración de axones in vivo. Se ha demostrado que el conducto de HA y las fibras de PLA mantienen la proliferación de las SC, las cuales forman una estructura cilíndica denominada 'vaina de SC' en la pared interna del lumen del conducto y a su vez crecen de forma direccional en las fibras de PLA. El conjunto unidireccional paralelo formado por las fibras PLA y las SC recapitula las características direccionales de los tractos axonales en el sistema nervioso. Al sembrar un explante de ganglio de la raíz dorsal (DRG) en uno de los extremos del conducto, se ha conseguido el crecimiento de los axones del DRG y se ha estudiado las características de las SC, los axones crecidos y su asociación, comprobando que el biohíbrido es capaz de soportar el crecimiento axonal. Además, se propone un concepto multimodular para superar las limitaciones típicas de la regeneración axonal a larga distancia, con la combinación de haces de fibras de PLA en el lumen de varios conductos o módulos de HA individuales más cortos que se posicionan uno detrás del otro, diseñando conductos nerviosos guiados con la longitud deseada, junto con SC pre-cultivadas. El conducto multimodular demostró ser eficaz para promover el crecimiento dirigido de axones. Además, se ha desarrollado un constructo compuesto por la estructura formada por las fibras de PLA y las SC, denominado 'cordón neural', tras eliminar el conducto de HA, lo que abre la puerta a la generación de una estructura neural in vitro para su trasplante. / [CA] Les lesions de el sistema nerviós que impliquen la interrupció de feixos axonals són devastadores per a l'individu. La regeneració autònoma dels tractes axonals danyats o degenerats és poc freqüent, ja que intervenen una gran quantitat de factors que limiten aquesta recuperació. Avui dia, la medicina convencional no compta amb tractaments efectius i reeixits per aquestes lesions, i el tractament dels símptomes sol ser la millor solució. Per revertir i aconseguir la reconnexió funcional de les neurones, l'enginyeria de teixits actualment opta per l'ús de suports tridimensionals biocompatibles, cèl·lules i molècules bioactives. Específicament, una de les estratègies proposades han estat els conductes nerviosos guiats, no només per lesions de nervis perifèrics sinó també per tractes de sistema nerviós central. En aquesta tesi doctoral, es proposa la combinació d'un conducte tubular buit d'àcid hialurònic (HA) farcit amb fibres d'àcid poli-L-lactida (PLA) en el seu lumen, i amb cèl·lules de Schwann (SC) pre-cultivades com a cèl·lules de suport de l'extension axonal per superar els obstacles que limiten la regeneració d'axons in vivo. S'ha demostrat que el conducte d'HA i les fibres de PLA mantenen la proliferació de les SC, les quals formen una estructura cilíndica anomenada 'beina de SC' a la paret interna de l'lumen de l'conducte i al seu torn creixen de manera direccional en les fibres de PLA. El conjunt unidireccional paral·lel format per les fibres PLA i les SC recapitula les característiques direccionals dels tractes axonals en el sistema nerviós. A l'sembrar un explantament de gangli de l'arrel dorsal (DRG) en un dels extrems de l'conducte, s'ha seguit el creixement dels axons de l'DRG i s'ha estudiat les característiques de les SC, els axons crescuts i la seva associació, comprovant que el biohíbrido és capaç de suportar el creixement axonal. A més, es proposa un concepte multimodular per superar les limitacions típiques de la regeneració axonal a llarga distància, amb la combinació de feixos de fibres de PLA en el lumen de diversos conductes o mòduls de HA individuals més curts que es posicionen un darrere l'l'altre, dissenyant conductes nerviosos guiats amb la longitud desitjada, juntament amb SC pre-cultivades. El conducte multimodular va demostrar ser eficaç per promoure el creixement dirigit d'axons. A més, s'ha desenvolupat un constructe format per l'estructura formada per les fibres de PLA i les SC, denominat 'cordó neural', després d'eliminar el conducte d'HA, el que obre la porta a la generació d'una estructura neural in vitro per al seu trasplantament. / [EN] Injuries to the nervous system that involve the disruption of axonal bundles are devastating to the individual. Autonomous regeneration of damaged or degenerated axonal tracts is infrequent since a large number of factors are involved limiting this recovery. Nowadays, conventional medicine does not have effective and successful treatments for these injuries, and the treatment of symptoms is often the best solution. In order to reverse it and achieve the functional reconnection of neurons, tissue engineering currently opts for the use of biocompatible three-dimensional supports, cells, and bioactive molecules. Specifically, one of the proposed strategies has been nerve guidance conduits, not only for peripheral nerve injuries but also for tracts of the central nervous system. In this Doctoral Thesis, we propose the combination of hyaluronic acid (HA) single-channel tubular conduit filled with poly-L-lactide acid (PLA) fibres in its lumen, with pre-cultured Schwann cells (SC) as cells supportive of axon extension to overcome the obstacles limiting axon regeneration in vivo. We have proved that HA conduit and PLA fibres sustain the proliferation of SC, which form a cylindrical structure named 'SC sheath' on the inner wall of the lumen of the conduit and in turn grow directionally in the PLA fibres. The parallel unidirectional ensemble formed by PLA fibres and SC recapitulates the directional features of axonal pathways in the nervous system. Planting a dorsal root ganglion (DRG) explant on one of the conduit's ends, we have followed axon outgrowth from the DRG and studied the features of SC, the grown axons and their association, checking that the biohybrid is capable of supporting axonal growth. Furthermore, we propose a multimodular concept to overcome the typical limitations of long-distance axonal regeneration, with the combination of PLA fibres bundle in the lumen of several shorter individual HA conduits or modules which positioned themselves one behind the other, designing nerve guided conduits with the desired length, together with pre-cultured SC. The multimodular conduit proved effective in promoting directed axon growth. Moreover, we developed a construct consisting of the structure formed by the PLA fibres and the SC, named 'neural cord', after eliminating the HA conduit, that opens the door to the generation of a neural structure in vitro for transplantation. / La presente tesis doctoral se ha realizado con la financiación del Ministerio de Economía y Competitividad a través de los proyectos MAT2015-66666-C3-1-R, DPI2015-72863-EXP, y AEI RTI2018-095872-B-C21-C22/ERDF. Agradezco también la beca FPU15/04975 al Ministerio de Educación Cultura y Deportes. / Rodríguez Doblado, L. (2021). Biohybrids for Neural Tracts Regeneration [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/165196 / TESIS

Les cellules de Schwann (CS) sont les cellules gliales myélinisantes du Système Nerveux Périphérique (SNP). Il existe une communication étroite entre ces cellules et les axones auxquels elles s’associent et ce dès les stades les plus précoces de leur développement. Elles migrent tout en se divisant le long des axones; cette division migratoire est suivie d’une deuxième division post-migratoire dans le but d’établir un ratio 1:1 avec les axones pour ensuite les myéliniser. Ce travail vise à analyser, in vivo, le comportement des CS chez le poisson zèbre au cours de leurs divisions.Nous avons remarqué que les CS se divisent parallèlement aux axones le long du nerf de la Ligne Latérale Postérieure (PLL). En analysant les deux mutants has et nok, nous avons montré que les gènes de polarité apicale aPKC et pals1 ne sont pas requis pour la migration et la division des CS, ni pour leur capacité à myéliniser. Nous avons mis en évidence, en analysant le mutant cassiopeia qui présente des défauts d’organisation du fuseau mitotique et en utilisant l’agent pharmacologique le nocodazole, que l’assemblage du fuseau mitotique au cours de la division des CS est essentiel pour la myélinisation.En parallèle, nous avons analysé le rôle du gène rgs4 (regulator of G-protein Signaling 4) dans le développement du SNP chez le poisson zèbre. Nous avons généré un mutant stable rgs4 par la technique CRISPR/Cas9 et montré un rôle de ce gène dans le développement du ganglion de la PLL et des motoneurones, et ce en agissant en amont de la voie PI3K/Akt/mTOR.Contrairement à l’inhibition pharmacologique qui suggère un rôle de rgs4 dans la myélinisation périphérique, le mutant ne présente pas de défauts de myéline. / Schwann cells (SCs) are the myelinating glial cells of the Peripheral Nervous System (PNS). They derive from neural crest cells during development, then migrate and divide along the axons of the peripheral nerves. This migratory division is followed by a post-migratory division in order to radially sort the axons in a 1:1 ratio and wrap them with a myelin sheath. This work provides an analysis of the polarity of SC divisions, in vivo, in intact zebrafish embryos.We showed that SCs divide parallel to the axons along the Posterior Lateral Line nerve (PLL). By analyzing the two mutants has and nok, we revealed that the apical polarity genes aPKC and pals1, are neither required for the migration and division of SCs, nor for their capacity to myelinate. By studying the cassiopeia mutant that shows defects in mitotic spindle, we revealed that the assembly of the mitotic spindle is essential for SC myelination.We have also analysed the role of rgs4 (regulator of G-protein Signaling 4) in PNS development. We generated a stable rgs4 mutant using the CRISPR/Cas9 technology. We showed that rgs4 plays an essentiel role in PLLg and motoneurons development by acting upstream of PI3K/Akt/mTOR pathway. Pharmacological analysis suggested a role for rgs4 in peripheral myelination, however, the rgs4 mutant do not show any myelin defects.

Parkinson’s disease (PD) is a disorder of the nervous system that causes problems with movement (motor symptoms) as well as other problems such as mood disorders, cognitive changes, sleep disorders, constipation, pain, and other non-motor symptoms. The severity of PD symptoms worsens over time as the disease progresses, and while there are treatments for the motor and some non-motor symptoms there is no known cure for PD. Thus there is a high demand for therapies to slow the progressive neurodegeneration observed in PD. Two clinical trials at the University of Kentucky College of Medicine (NCT02369003, NCT01833364) are currently underway that aim to develop a disease-modifying therapy that slows the progression of PD. These clinical trials are evaluating the safety and feasibility of an autologous peripheral nerve graft to the substantia nigra in combination with Deep Brain Stimulation (DBS) for the treatment of PD. By grafting peripheral nerve tissue to the Substantia Nigra, the researchers aim to introduce peripheral nerve tissue, which is capable of functional regeneration after injury, to the degenerating Substantia Nigra of patients with PD. The central hypothesis of these clinical trials is that the grafted tissue will slow degeneration of the target brain region through neural repair actions of Schwann cells as well as other pro-regenerative features of the peripheral nerve tissue. This dissertation details analysis of the peripheral nerve tissue used in the above clinical trials with respect to tissue composition and gene expression, both of injury-naive human peripheral nerve as well as the post-conditioning injury nerve tissue used in the grafting procedure. RNA-seq analysis of sural nerve tissue pre and post-conditioning show significant changes in gene expression corresponding with transdifferentiation of Schwann cells from a myelinating to a repair phenotype, release of growth factors, activation of macrophages and other immune cells, and an increase in anti-apoptotic and neuroprotective gene transcripts. These results reveal in vivo gene expression changes involved in the human peripheral nerve injury repair process, which has relevance beyond this clinical trial to the fields of Schwann cell biology and peripheral nerve repair. To assess the neurobiology of the graft post-implantation we developed an animal model of the grafting procedure, termed Neuro-Avatars, which feature human graft tissue implanted into athymic nude rats. Survival and infiltration of human graft cells into the host brain were shown using immunohistochemistry of Human Nuclear Antigen. Surgical methods and outcomes from the ongoing development of this animal model are reported. To connect the results of these laboratory studies to the clinical trial we compared the severity of motor symptoms before surgery to one year post-surgery in patients who received the analyzed graft tissue. Motor symptom severity was assessed using the Unified Parkinson’s Disease Rating Scale Part III. Finally, the implications and future directions of this research is discussed. In summary, this dissertation advances the translational science cycle by using clinical trial findings and samples to answer basic science questions that will in turn guide future clinical trial design.