The adsorption of a peptide (NFL-TBS.40-63 peptide (NFL)) known to induce neural stem cells (NSC) differentiation in vitro, at the surface of lipid nanocapsules (LNC) provides a targeting drug delivery system (NFL-LNC) that penetrates subventricular zone-neural stem cells (SVZ-NSC) but not central canal-NSC (CC-NSC). We hypothesized preferential interactions could explaine, at least partially, the different properties of SVZ- and CC-NSC plasma membranes. The objective of this work was to compare SVZ- and CC-NSC plasma membrane lipid composition, fluidity and permeability. Plasma membranes of SVZ- and CC-NSC were isolated and analyzed by LC-MS for their lipid content. Membrane fluidity was evaluated by measuring the generalized polarization (GP) of Laurdan and membrane permeability by fluorescent dextran penetration. Liposomes with different lipid compositions and steady state fluidities were prepared. ΔGP was measured after incubation with NFL-LNC. A significantly higher proportion of cholesterol, ceramides, sphingomyelins, phosphatidylethanolamines and a lower proportion of phosphatidylcholines and sulfatides were observed in SVZ- compared to CC-NSC. Fluidity, probably more than lipid composition, drove NFL-LNC and NSC interactions, and SVZ-NSC were more sensitive to NFL permeabilization than CC-NSC. We demonstrated that NSC membrane lipid composition and fluidity depended of NSC origin and that these features could play a role in the specific interactions with NFL-LNC.

While in mice various studies have described the completion of spermatogenesis in vitro using either organotypic culture of prepubertal testicular tissue or 3D culture of isolated cells, in humans it has not been possible to achieve germ cell differentiation from immature testicular tissue (ITT). In our study, we evaluated the ability of human ITT to differentiate via a long-term organotypic culture of frozen-thawed 1 mm3 testicular fragments from five prepubertal boys in two different culture media. Tissue and supernatants were analyzed at regular intervals up to day 139. Sertoli cell (SC) viability and maturation was evaluated using immunohistochemistry (IHC) for SOX9, GDNF, anti-Mullerian hormone (AMH) and androgen receptor (AR), and AMH concentration in supernatants. Spermatogonia (SG) and proliferating cells were identified by MAGE-A4 (for SG) and Ki67 (for proliferating cells) via immunohistochemistry (IHC). Apoptotic cells were studied by active caspase 3. To evaluate Leydig cell (LC) functionality testosterone was measured in the supernatants and steroidogenic acute regulatory protein (STAR) IHC was performed. Germ cell differentiation was evaluated on Hematoxylin-Eosin histological sections, via IHC for synaptonemal complex 3 (SYCP3) for spermatocytes, Protein boule-like (BOLL) for spermatocytes and round spermatids, angiotensin-converting enzyme (ACE), protamine 2 and transition protein 1 (for elongated spermatids) and via chromogenic in situ hybridization (CISH). We reported the generation of meiotic and postmeiotic cells after 16 days of culture, as shown by the histological analyses, the presence of differentiation markers and the increase of haploid germ cells. We showed SC viability and maturation by a decrease of AMH secretion in the supernatants (p ≤ 0.001) while the number of SOX9 positive cells did not show any variation. A decrease of spermatogonia (p ≤ 0.001) was observed. The number of apoptotic cells did not vary. LC functionality was shown by the increase in STAR expression (p ≤ 0.007) and a peak in testosterone secretion, followed by a reduction (p ≤ 0.001) with stabilization. According to our knowledge, this is the first report of generation of haploid cells in human ITT. Differentiating germ cells have to be further evaluated for their ability to complete differentiation, their fecundability and epigenetic characteristics.

Failed regeneration of CNS myelin contributes to clinical decline in neuroinflammatory and neurodegenerative diseases, for which there is an unmet therapeutic need. Here we reveal that efficient remyelination requires death of proinflammatory microglia followed by repopulation to a pro-regenerative state. We propose that impaired microglia death and/or repopulation may underpin dysregulated microglia activation in neurological diseases, and we reveal therapeutic targets to promote white matter regeneration.

The lack of robust methods to preserve, purify and in vitro maintain the phenotype of the human liver's highly specialized parenchymal and non-parenchymal cell types importantly hampers their exploitation for the development of research and clinical applications. There is in this regard a growing interest in the use of tissue-specific extracellular matrix (ECM) to provide cells with an in vitro environment that more closely resembles that of the native tissue. In the present study, we have developed a method that allows for the isolation and downstream application of the human liver's main cell types from cryopreserved material. We also isolated and solubilized human liver ECM (HL-ECM), analyzed its peptidomic and proteomic composition by mass spectrometry and evaluated its interest for the culture of distinct primary human liver cells. Our analysis of the HL-ECM revealed proteomic diversity, type 1 collagen abundance and partial loss of integrity following solubilization. Solubilized HL-ECM was evaluated either as a coating or as a medium supplement for the culture of human primary hepatocytes, hepatic stellate cells and liver sinusoidal endothelial cells. Whereas the solubilized HL-ECM was suitable for cell culture, its impact on the phenotype and/or functionality of the human liver cells was limited. Our study provides a first detailed characterization of solubilized HL-ECM and a first report of its influence on the culture of distinct human primary liver cells.

Reactive microgliosis is an important pathological component of neuroinflammation and has been implicated in a wide range of brain diseases including brain tumors, multiple sclerosis, Parkinson's disease, Alzheimer's disease, and schizophrenia. Mapping reactive microglia in-vivo is often performed with PET scanning whose resolution, cost, and availability prevent its widespread use. The advent of diffusion compartment imaging (DCI) to probe tissue microstructure in vivo holds promise to map reactive microglia using MRI scanners. But this potential has never been demonstrated. In this paper, we performed longitudinal DCI in rats that underwent dorsal root axotomy triggering Wallerian degeneration of axons-a pathological process which reliably activates microglia. After the last DCI at 51 days, rats were sacrificed and histology with Iba-1 immunostaining for microglia was performed. The fraction of extra-axonal restricted diffusion from DCI was found to follow the expected temporal dynamics of reactive microgliosis. Furthermore, a strong and significant correlation between this parameter and histological measurement of microglial density was observed. These findings strongly suggest that extra-axonal restricted diffusion is an in-vivo marker of reactive microglia. They pave the way for MRI-based microglial mapping which may be important to characterize the pathogenesis of neurological and psychiatric diseases.

CXCL12 is a chemokine known to regulate migration, proliferation, and differentiation of neural stem cells (NSCs) and to play a neuroprotective role in ischemic stroke. Chitosan-dextran sulfate nanocomplexes (Ch/DS NC) are known nanoparticulated systems used to efficiently deliver heparin-binding factors. Here we evaluate Ch/DS NC as carriers for CXCL12 in a mouse model of stroke. Free CXCL12 reduced the size of the ischemic brain lesion. However, when Ch/DS NC were administrated, the stroke volume increased. Neurotoxic screening revealed that Ch/DS NC reduced neuronal viability, decreased the extension of neurites and impaired NSC migration in vitro. To the best of our knowledge, neurotoxicity of Ch/DS NC has not been reported and further screenings will be needed in order to evaluate the biological safety of these nanocomposites. Our results add new data on nanoparticle neurotoxicity and may help us to better understand the complex interactions of the nanostructures with biological components.

In vitro and in vivo models of experimental glioma are useful tools to gain a better understanding of glioblastoma (GBM) and to investigate novel treatment strategies. However, the majority of preclinical models focus on treating solid intracranial tumours, despite surgical resection being the mainstay in the standard care of patients with GBM today. The lack of resection and recurrence models therefore has undermined efforts in finding a treatment for this disease. Here we present a novel orthotopic tumour resection and recurrence model that has potential for the investigation of local delivery strategies in the treatment of GBM. The model presented is simple to achieve through the use of a biopsy punch, is reproducible, does not require specific or expensive equipment, and results in a resection cavity suitable for local drug delivery systems, such as the implantation or injection of hydrogels. We show that tumour resection is well tolerated, does not induce deleterious neurological deficits, and significantly prolongs survival of mice bearing U-87 MG GBM tumours. In addition, the resulting cavity could accommodate adequate amounts of hydrogels for local delivery of chemotherapeutic agents to eliminate residual tumour cells that can induce tumour recurrence.

Neural stem cells (NSC) are located in restricted areas of the central nervous system where they self-renew or differentiate into neurons, astrocytes or oligodendrocytes. The stimulation of endogenous NSC differentiation is one of the most promising therapeutic approaches to restore neurological function in patients affected by neurodegenerative diseases. Endogenous NSC of the subventricular zone (SVZ) can be selectively targeted by lipid nanocapsules (LNC) coated with the peptide NFLTBS.40-63 (NFL-LNC) after intra-lateral ventricular injection in the brain. NFL-LNC can potentially deliver active compounds to SVZ-NSC and thus promote their differentiation to treat neurodegenerative diseases. The aim of this work was to induce endogenous NSC differentiation by specifically delivering retinoic acid (RA) to SVZ-NSC via NFL-LNC. RA was successfully encapsulated into NFL-LNC and RA-NFL-LNC were incubated with primary rat SVZ-NSC. In vitro, RA-NFL-LNC decreased the number of nestin+ (NSC marker) cells and neurospheres compared to controls and increased the number of GalC+ (oligodendrocytic marker) cells. Then, RA-NFL-LNC were injected in the right lateral ventricle of a lysolecithin-induced rat focal white matter lesion model to evaluate their impact on oligodendrocyte repopulation and remyelination. RA-NFL-LNC significantly increased the percentage of mature oligodendrocytes, stimulating oligodendrogenesis, nearly to the pre-lesion levels. Thus, RA-NFL-LNC represent a promising nanomedicine to be further investigated in the treatment of demyelinating diseases.

The most prevalent neurological disorders of myelin include perinatal brain injury leading to cerebral palsy in infants and multiple sclerosis in adults. Although these disorders have distinct etiologies, they share a common neuropathological feature of failed progenitor differentiation into myelin-producing oligodendrocytes and lack of myelin, for which there is an unmet clinical need. Here, we reveal that a molecular pathology common to both disorders is dysregulation of activin receptors and that activin receptor signaling is required for the majority of myelin generation in development and following injury. Using a constitutive conditional knockout of all activin receptor signaling in oligodendrocyte lineage cells, we discovered this signaling to be required for myelination via regulation of oligodendrocyte differentiation and myelin compaction. These processes were found to be dependent on the activin receptor subtype Acvr2a, which is expressed during oligodendrocyte differentiation and axonal ensheathment in development and following myelin injury. During efficient myelin regeneration, Acvr2a upregulation was seen to coincide with downregulation of Acvr2b, a receptor subtype with relatively higher ligand affinity; Acvr2b was shown to be dispensable for activin receptor-driven oligodendrocyte differentiation and its overexpression was sufficient to impair the abovementioned ligand-driven responses. In actively myelinating or remyelinating areas of human perinatal brain injury and multiple sclerosis tissue, respectively, oligodendrocyte lineage cells expressing Acvr2a outnumbered those expressing Acvr2b, whereas in non-repairing lesions Acvr2b+ cells were increased. Thus, we propose that following human white matter injury, this increase in Acvr2b expression would sequester ligand and consequently impair Acvr2a-driven oligodendrocyte differentiation and myelin formation. Our results demonstrate dysregulated activin receptor signaling in common myelin disorders and reveal Acvr2a as a novel therapeutic target for myelin generation following injury across the lifespan.

Klinefelter Syndrome (KS) is the most common genetic cause of infertility in men. Degeneration of the testicular tissue starts in utero and accelerates at puberty with hyalinisation of seminiferous tubules, spermatogonia apoptosis and germ cell maturation arrest. Therefore, fertility preservation in young KS boys has been proposed, although this measure is still debated due to insufficient knowledge of the pathophysiology of the disease. To better understand the underlying mechanisms of testicular failure and germ cell loss, we analysed functional and morphological alterations in the somatic compartment of KS testis, i.e., Sertoli cells, including the blood-testis barrier (BTB) and Leydig cells (LC). We compared three populations: 35 KS 47,XXY non-mosaic patients, 28 Sertoli-cell-only (SCO) syndrome patients and 9 patients with normal spermatogenesis. In KS patients the expression of BTB proteins connexin-43 and claudin-11 assessed with a semi-quantitative scoring system appeared significantly reduced with a disorganised pattern. A significant reduction in seminiferous tubules expressing androgen receptors (AR) was observed in KS compared to normal spermatogenesis controls. INSL3 expression, a marker of LC maturation, was also significantly reduced in KS compared to patients with normal spermatogenesis or SCO. Hence, the somatic compartment impairment in KS could be involved in degeneration of seminiferous tubules.

Avascular transplantation of frozen-thawed testicular tissue fragments represents a potential future technique for fertility restoration in boys with cancer. A significant loss of spermatogonia was observed in xeno-transplants of human tissue most likely due to the hypoxic period before revascularization. To reduce the effect of hypoxia-reoxygenation injuries, several options have already been explored, like encapsulation in alginate hydrogel and supplementation with nanoparticles delivering a necrosis inhibitor (NECINH) or VEGF. While these approaches improved short-term (5 days) vascular surfaces in grafts, neovessels were not maintained up to 21 days; i.e., the time needed for achieving vessel stabilization. To better support tissue grafts, nanoparticles loaded with VEGF, PDGF and NECINH were developed. Testicular tissue fragments from 4-5-week-old mice were encapsulated in calcium-alginate hydrogels, either non-supplemented (control) or supplemented with drug-loaded nanoparticles (VEGF-nanoparticles; VEGF-nanoparticles + PDGF-nanoparticles; NECINH-nanoparticles; VEGF-nanoparticles + NECINH-nanoparticles; and VEGF-nanoparticles + PDGF-nanoparticles + NECINH-nanoparticles) before auto-transplantation. Grafts were recovered after 5 or 21 days for analyses of tissue integrity (hematoxylin-eosin staining), spermatogonial survival (immuno-histo-chemistry for promyelocytic leukemia zinc finger) and vascularization (immuno-histo-chemistry for α-smooth muscle actin and CD-31). Our results showed that a combination of VEGF and PDGF nanoparticles increased vascular maturity and induced a faster maturation of vascular structures in grafts.

Objective: To describe the available knowledge on vulvo-perineal endometriosis including its diagnosis, clinical management and recurrence rate. Methods: We followed the PRISMA guidelines for Systematic Reviews and our study was prospectively registered with PROSPERO (CRD42020202441). The terms "Endometriosis" and "Perineum" or "Vulva" were used as keywords. Cochrane Library, Medline/Pubmed, Embase and Clinicaltrials.gov were searched. Papers in English, Spanish, Portuguese, French or Italian from inception to July 30, 2020 were considered. Reference lists of included articles and other literature source such as Google Scholar were also manually scrutinized in order to identify other relevant studies. Two independent reviewers screened potentially eligible studies according to inclusion criteria. Results: Out of 539 reports, 90 studies were eligible including a total of 283 patients. Their mean age was 32.7 ± 7.6 years. Two hundred sixty-three (95.3%) presenting with vulvo-perineal endometriosis have undergone either episiotomy, perineal trauma or vaginal injury or surgery. Only 13 patients (4.7%) developed vulvo-vaginal endometriosis spontaneously i.e., without any apparent condition favoring it. The reasons that motivated the patients to take medical advice were vulvo-perineal cyclical pain increasing during menstruations (98.2% of the patients, n = 278). Out of the 281 patients for whom a clinical examination was described, 274 patients (97.5%) showed a vulvo-perineal nodule, mass or swelling while six presented with bluish cutaneous lesions (2.1%) and 1 with bilateral polyps of the labia minora (0.4%). All but one patients underwent surgical excision of their lesions but only 88 patients (28.1%) received additional hormonal therapy. The recurrence rate was 10.2% (29 patients) considering a median follow-up period of 10 months (based on 61 studies). Conclusion: In conclusion, vulvo-perineal endometriosis is a rare entity with approximately 300 cases reported in the literature since 1923. With the available knowledge shown in this systematic review, we encourage all practitioners to think about perineal endometriosis in case of perineal cyclical pain with or without previous perineal damage. Diagnosis should be done with clinical exam, perineal ultrasound and pelvic MRI when available. In case of anal sphincter involvement, perianal ultrasound should be performed. Surgical excision of the lesion should be realized in order to remove the lesion and to confirm the diagnosis histologically. Hormonal treatment could be proposed to attempt to decrease the size of a large lesion before surgery or to avoid recurrence of the lesion. As evidence-based approach to the diagnosis, treatment and recurrence rate of affected patients remains a challenge given its low prevalence, the variations in management found in the articles included and the limited quality of available studies, we suggest that a prospective database on vulvo-perineal endometriosis should be generated to increase knowledge but also awareness among healthcare professionals and optimize patients' care. Systematic Review Registration: https://www.crd.york.ac.uk/prospero/, identifier: CRD42020202441.

Sperm DNA fragmentation (SDF) testing was recently added to the sixth edition of the World Health Organization laboratory manual for the examination and processing of human semen. Many conditions and risk factors have been associated with elevated SDF; therefore, it is important to identify the population of infertile men who might benefit from this test. The purpose of this study was to investigate global practices related to indications for SDF testing, compare the relevant professional society guideline recommendations, and provide expert recommendations.

Cryopreservation of immature testicular tissue before chemo/radiotherapy is the only option to preserve fertility of cancer-affected prepubertal boys. To avoid reintroduction of malignant cells, development of a transplantable scaffold by decellularization of pig immature testicular tissue (ITT) able to support decontaminated testicular cells could be an option for fertility restoration in these patients. We, therefore, compared decellularization protocols to produce a cytocompatible scaffold. Fragments of ITT from 15 piglets were decellularized using three protocols: sodium dodecyl sulfate (SDS)-Triton (ST), Triton-SDS-Triton (TST) and trypsin 0.05%/ethylenediaminetetraacetic acid (EDTA) 0.02%-Triton (TET) with varying detergent concentrations. All protocols were able to lower DNA levels. Collagen retention was demonstrated in all groups except ST 1%, and a significant decrease in glycosaminoglycans was observed in the TST 1% and TET 1% groups. When Sertoli cells (SCs) were cultured with decellularized tissue, no signs of cytotoxicity were detected. A higher SC proliferation rate and greater stem cell factor secretion were observed than with SCs cultured without scaffold. ST 0.01% and TET 3% conditions offered the best compromise in terms of DNA elimination and extracellular matrix (ECM) preservation, while ensuring good attachment, proliferation and functionality of human SCs. This study demonstrates the potential of using decellularized pig ITT for human testicular tissue engineering purposes.

After spinal cord injury (SCI) chronic inflammation hampers regeneration. Influencing the local microenvironment after SCI may provide a strategy to modulate inflammation and the immune response. The objectives of this work were to determine whether bone or spinal cord derived ECM hydrogels can deliver human mesenchymal stem cells from the apical papilla (SCAP) to reduce local inflammation and provide a regenerative microenvironment. Bone hydrogels (8 and 10 mg/ml, B8 and B10) and spinal cord hydrogels (8 mg/ml, S8) supplemented with fibrin possessed a gelation rate and a storage modulus compatible with spinal cord implantation. S8 and B8 impact on the expression of anti and pro-inflammatory cytokines (Arg1, Nos2, Tnf) in LPS treated microglial cells were assessed using solubilised and solid hydrogel forms. S8 significantly reduced the Nos2/Arg1 ratio and solubilised B8 significantly reduced Tnf and increased Arg1 whereas solid S8 and B8 did not impact inflammation in microglial cells. SCAP incorporation within ECM hydrogels did not impact upon SCAP immunoregulatory properties, with significant downregulation of Nos2/Arg1 ratio observed for all SCAP embedded hydrogels. Tnf expression was reduced with SCAP embedded in B8, reflecting the gene expression observed with the innate hydrogel. Thus, ECM hydrogels are suitable vehicles to deliver SCAP due to their physical properties, preservation of SCAP viability and immunomodulatory capacity.

Klinefelter syndrome (KS), with an incidence between 1/600 and 1/1,000, is the main genetic cause of male infertility. Due to the lack of an accurate study model, the detailed pathogenic mechanisms by which this X chromosome aneuploidy leads to KS features remain unknown. Here, we report the generation and characterization of induced pluripotent stem cells (iPSCs) derived from a patient with KS: 47XXY-iPSCs. In order to compare the potentials of both 47XXY-iPSCs and 46XY-iPSCs to differentiate into the germ cell lineage, we developed a directed differentiation protocol by testing different combinations of factors including bone morphogenetic protein 4 (BMP4), glial-derived neurotrophic factor (GDNF), retinoic acid (RA) and stem cell factor (SCF) for 42 days. Importantly, we found a reduced ability of 47XXY-iPSCs to differentiate into germ cells when compared to 46XY-iPSCs. In particular, upon germ cell differentiation of 47XXY-iPSCs, we found a reduced proportion of cells positive for BOLL, a protein required for germ cell development and spermatogenesis, as well as a reduced proportion of cells positive for MAGEA4, a spermatogonia marker. This reduced ability to generate germ cells was not associated with a decrease of proliferation of 47XXY-iPSC-derived cells but rather with an increase of cell death upon germ cell differentiation as revealed by an increase of LDH release and of capase-3 expression in 47XXY-iPSC-derived cells. Our study supports the idea that 47XXY-iPSCs provides an excellent in vitro model to unravel the pathophysiology and to design potential treatments for KS patients.

There is no treatment for spinal cord injury (SCI) that fully repairs the damages. One strategy is to inject mesenchymal stem cells around the lesion to benefit from their immunomodulatory properties and neuroprotective effect. Our hypothesis was that the combination of dental stem cells from the apical papilla (SCAP) with pharmacologically active microcarriers (PAMs) releasing brain-derived neurotrophic factor (BDNF) would improve rat locomotor function by immunomodulation and neuroprotection. BDNF-PAMs were prepared by solid/oil/water emulsion of poly(L-lactide-co-glycolide) and nanoprecipitated BDNF and subsequent coating with fibronectin. SCAP were then seeded on BDNF-PAMs. SCAP expression of neuronal and immunomodulatory factors was evaluated in vitro. SCAP BDNF-PAMs were injected in a rat spinal cord contusion model and their locomotor function was evaluated by Basso, Beattie, and Bresnahan (BBB) scoring. Impact on inflammation and neuroprotection/axonal growth was evaluated by immunofluorescence. Culture on PAMs induced the overexpression of immunomodulatory molecules and neural/neuronal markers. Injection of SCAP BDNF-PAMs at the lesion site improved rat BBB scoring, reduced the expression of inducible nitric oxide synthase and increased the expression of βIII tubulin, GAP43, and 5-HT. These results confirm the suitability and versatility of PAMs as combined drug and cell delivery system for regenerative medicine applications but also that BDNF-PAMs potentialize the very promising therapeutic potential of SCAP in the scope of SCI.

Tactile hypersensitivity is one of the most debilitating symptoms of neuropathic pain syndromes. Clinical studies have suggested that its presence at early postoperative stages may predict chronic (neuropathic) pain after surgery. Currently available animal models are typically associated with consistent tactile hypersensitivity and are therefore limited to distinguish between mechanisms that underlie tactile hypersensitivity as opposed to mechanisms that protect against it. In this study we have modified the rat model of spared nerve injury, restricting the surgical lesion to a single peripheral branch of the sciatic nerve. This modification reduced the prevalence of tactile hypersensitivity from nearly 100% to approximately 50%. With this model, we here also demonstrated that the Regulator of G protein Signaling 4 (RGS4) was specifically up-regulated in the lumbar dorsal root ganglia and dorsal horn of rats developing tactile hypersensitivity. Intrathecal delivery of the RGS4 inhibitor CCG63802 was found to reverse tactile hypersensitivity for a 1h period. Moreover, tactile hypersensitivity after modified spared nerve injury was most frequently persistent for at least four weeks and associated with higher reactivity of glial cells in the lumbar dorsal horn. Based on these data we suggest that this new animal model of nerve injury represents an asset in understanding divergent neuropathic pain outcomes, so far unravelling a role of RGS4 in tactile hypersensitivity. Whether this model also holds promise in the study of the transition from acute to chronic pain will have to be seen in future investigations.

Despite their important contribution to the cure of both oncological and benign diseases, gonadotoxic therapies present the risk of a severe impairment of fertility. Sperm cryopreservation is not an option to preserve prepubertal boys' reproductive potential, as their seminiferous tubules only contain spermatogonial stem cells (as diploid precursors of spermatozoa). Cryobanking of human immature testicular tissue (ITT) prior to gonadotoxic therapies is an accepted practice. Evaluation of cryopreserved ITT using xenotransplantation in nude mice showed the survival of a limited proportion of spermatogonia and their ability to proliferate and initiate differentiation. However, complete spermatogenesis could not be achieved in the mouse model. Loss of germ cells after ITT grafting points to the need to optimize the transplantation technique. Tissue engineering, a new branch of science that aims at improving cellular environment using scaffolds and molecules administration, might be an approach for further progress. In this review, after summarizing the lessons learned from human prepubertal testicular germ cells or tissue xenotransplantation experiments, we will focus on the benefits that might be gathered using bioengineering techniques to enhance transplantation outcomes by optimizing early tissue graft revascularization, protecting cells from toxic insults linked to ischemic injury and exploring strategies to promote cellular differentiation.

Impairment of oligodendrocyte progenitor cell (OPC) differentiation into oligodendrocytes and chronic inflammation are key determinants of poor remyelination observed in diseases such as multiple sclerosis. For many pro-myelinating molecules, the therapeutic potential is hindered by poor solubility or limited access to the targeted cells. A promising approach to improve the delivery of those molecules to OPC is to encapsulate them in functionalized Lipid Nanocapsules (LNC). We aimed to develop the first OPC-targeting LNC, by grafting an anti-PDGFRα antibody on the surface of the LNC using several strategies and evaluating the interaction with PDGFRα via ELISA. We found that only site-selective click-chemistry grafting maintained anti-PDGFRα/PDGFRα association, which was confirmed in vitro on primary rat OPC. In conclusion, we demonstrated that it was possible to produce anti-PDGFRα functionalized LNC, we confirmed the antibody's ability to recognize its receptor after grafting and we optimized techniques to characterize antibody functionalized LNC.