The role of olfactory ensheathing cells in the repair of nerve injury

Cell transplantation has brought about a breakthrough in the treatment of nerve injuries, and the efficacy of cell transplantation compared to drug and surgical therapies is very exciting. In terms of transplantation targets, the classic cells include neural stem cells (NSCs) and Schwann cells, while a class of cells that can exist and renew throughout the life of the nervous system - olfactory ensheathing cells (OECs) - has recently been discovered in the olfactory system. OECs not only encircle the olfactory nerves but also act as macrophages and play an innate immune role. OECs can also undergo reprogramming to transform into neurons and survive and mature after transplantation. Currently, many studies have confirmed the repairing effect of OECs after transplantation into injured nerves, and safe and effective results have been obtained in clinical trials. However, the specific repair mechanism of OECs among them is not quite clear. For this purpose, we focus here on the repair mechanisms of OECs, which are summarized as follows: neuroprotection, secretion of bioactive factors, limitation of inflammation and immune regulation, promotion of myelin and axonal regeneration, and promotion of vascular proliferation. In addition, integrating the aspects of harvesting, purification, and prognosis, we found that OECs may be more suitable for transplantation than NSCs and Schwann cells, but this does not completely discard the value of these classical cells. Overall, OECs are considered to be one of the most promising transplantation targets for the treatment of nerve injury disorders.

Transplantation of olfactory ensheathing cells can alleviate neuroinflammatory responses in rats with trigeminal neuralgia

Trigeminal neuralgia (TN) is a common form of facial pain, which primarily manifests as severe pain similar to facial acupuncture and electric shock. Olfactory ensheathing cells (OECs) are glial cells with high bioactivity; these cells are essential for the periodic regeneration of the olfactory nerve and have been utilized for the repair of nerve injuries. A member of the P2X receptor family, P2X7R, is an ion channel type receptor that has been confirmed to participate in various pain response processes. In this study, we transplanted OECs into trigeminal nerve-model rats with distal infraorbital nerve ligation to observe the therapeutic effect of transplanted OECs in rats. Additionally, we utilized the P2X7R-specific inhibitor brilliant blue G (BBG) to study the therapeutic mechanisms of cell transplantation. The facial mechanical pain threshold of these rats significantly increased following cell transplantation. The immunohistochemistry, immunoblotting, and RT-qPCR results demonstrated that the levels of P2X7R, (NOD)-like receptor protein-3 (NLRP3), nuclear factor-κB (NF-κB), interleukin (IL)-1β, and IL-18 in the trigeminal ganglion of rats treated with OEC transplantation or BBG treatment were significantly lower than those in the injured group without treatment. Overall, our results demonstrate that OEC transplantation can alleviate TN in rats, and it can reduce the expression of P2X7R related inflammatory factors in TN rats, reducing neuroinflammatory response in TG.

Effect of valproic acid combined with transplantation of olfactory ensheathing cells modified by neurotrophic 3 gene on nerve protection and repair after traumatic brain injury

BACKGROUND

Traumatic brain injury (TBI) often leads to cognitive and neurological dysfunction. Valproic acid (VPA) has a neuroprotective effect in acute central nervous system diseases; the neurotrophin 3 gene (NT-3) can maintain the survival of neurons, and olfactory ensheathing cells (OECs) can promote the growth of nerve axons. This study aimed to evaluate the restorative effect of VPA combined with NT-3 modified OECs (NT-3-OECs) on neurological function after TBI.

METHODS

The neurological severity score (NSS) of rats was evaluated on the 1st, 7th, 14th, and 28th day after TBI modeling and corresponding intervention. Hematoxylin-eosin (HE) staining, p75 nerve growth factor receptor (P75), glial fibrillary acidic protein (GFAP), and neurofilament protein (NF)staining, and argyrophilic staining were used to observe the morphology of brain tissue 28 days after modeling. Moreover, TdT-mediated dUTP Nick-End Labeling (TUNEL) was used to detect the apoptosis rate of neurons. The changes in synapses and mitochondria in the injured area were observed by electron microscope.

RESULTS

NT-3-OECs transplantation can increase the content of NT-3 in brain tissue, and NT-3-OECs can survive for >28 days. The NSS score of the TBI-VPA-NT-3-OECs group 28 days after cell transplantation was significantly lower than that of the other model treatment groups (P < 0.05). The morphological structure of the brain tissue was more complete, and the neurofilament fibers were neatly arranged, achieving better results than those of the other groups. The apoptosis rate of nerve cells in the TBI-VPA-NT-3-OECs group was significantly lower than in the other treatment groups (P < 0.05). Furthermore, the number of synapses in the combined intervention group was significantly higher than in the other treatment groups, and the mitochondrial structure was more complete.

CONCLUSION

NT-3-OECs have good biological function, and VPA combined with NT-3-OECs transplantation can effectively improve the prognosis of TBI rats.

Transpupillary-Guided Trans-Scleral Transplantation of Subretinal Grafts in a Retinal Degeneration Mouse Model

Transplantation of photoreceptor cells and retinal pigment epithelial (RPE) cells provide a potential therapy for retinal degeneration diseases. Subretinal transplantation of therapeutic donor cells into mouse recipients is challenging due to the limited surgical space allowed by the small volume of the mouse eye. We developed a trans-scleral surgical transplantation platform with direct transpupillary vision guidance to facilitate the subretinal delivery of exogenous cells in mouse recipients. The platform was tested using retinal cell suspensions and three-dimensional retinal sheets collected from rod-rich Rho::EGFP mice and cone-rich OPN1LW-EGFP;NRL-/- mice, respectively. Live/dead assay showed low cell mortality for both forms of donor cells. Retinal grafts were successfully delivered into the subretinal space of a mouse model of retinal degeneration, Rd1/NS, with minimum surgical complications as detected by multimodal confocal scanning laser ophthalmoscope (cSLO) imaging. Two months post-transplantation, histological staining demonstrated evidence of advanced maturation of the retinal grafts into 'adult' rods and cones (by robust Rho::EGFP, S-opsin, and OPN1LW:EGFP expression, respectively) in the subretinal space. Here, we provide a surgical platform that can enable highly accurate subretinal delivery with a low rate of complications in mouse recipients. This technique offers precision and relative ease of skill acquisition. Furthermore, the technique could be used not only for studies of subretinal cell transplantation but also for other intraocular therapeutic studies including gene therapies.

Use of hepatocyte transplantation after extensive liver resections in experiment

he aim of our research is to prove, that the transplanted hepatocytes can survive and compensate for inadequate liver function in experimental animals. Thesis discusses the basic principles of hepatocyte transplantations, the process of their adaptation and effect on the organism as well as possibilities of their further use as a promising treatment method.In the experiment we used hepatocytes isolated and produced from explanted livers of laboratory rats. Hepatocytes form the basis of liver tissue and are responsible for a number of metabolic processes ocurring in the liver, therefore is the possibility of their use as a cell therapy one of the alternative treatment methods for liver failure.Into the laboratory experiment, rats of the Sprague Dawleyspecies were placed, which we divided into five groups of equal numbers. Groups consisted of healthy rats, rats after 2/3 liver resection and rats with liver damage induced by intraperitoneal administration of thioacetamide.Two groups with impaired liver had hepatocytes prepared in advance transplanted into their portal vein.Hepatocyte function was assessed in the blood serum and compared with a control group of healthy animals and groups with liver damage without the application of hepatocytes at the same time intervals.Whole experiment lasted 21 days. On the last day of the experiment all the animals were killed by decapitation.Livers of all animals were explanted and sent for histopathological analysis which used classical histological methods. After evaluating the results we observed significant changes of evaluated laboratory levels in blood serum and weight in experimental animals after the transplantation of hepatocytes in comparison with the laboratory results of the control group of healthy animals and groups with liver damage without transplanted hepatocytes. The results of our experiment show that by biochemical and histological analysis we managed to clearly prove the function of transplanted hepatocytes in the model of laboratory rat with impaired liver function (Tab. 5, Fig. 17 , Ref. 17) Keywords: liver, transplantation, hepatocytes, liver tumors, resection of liver, liver failure, experiment.

Autologous cell transplant as a treatment for stable segmental vitiligo: a systematic review

OBJECTIVE

This systematic review provides a comprehensive analysis of the efficacy of autologous cell transplant as a therapeutic approach for stable segmental vitiligo. Vitiligo poses significant challenges for healthcare professionals in terms of treatment selection. Autologous cell transplant has emerged as a promising modality for managing vitiligo, with cultured and noncultured transplants being considered when determining the patient's treatment approach. There is little knowledge and literature on the subject, so we analyze the different studies.

METHOD

Using online medical literature databases and the PRISMA guidelines, six out of 60 articles met the acceptance criteria to be analyzed, emphasizing the lack of current literature on this subject.

RESULTS

Autologous cell transplant achieves excellent pigmentation rates for many body parts. We found that cultivated cells had better results than noncultivated ones. Both types of treatments could pigment 80% or more where needed.

CONCLUSION

This review highlights the importance of autologous cell transplant as a new and reliable tool for the treatment of stable segmental vitiligo, cultured transplants being the most effective. By employing autologous cell transplant, the repigmentation rate is notably high and consistently achievable. Although its cost and logistical complexities hinder the current accessibility to this therapy, efforts are being made to enhance its availability, and its scope is expected to expand further. More studies are needed to understand this therapy method in other kinds of vitiligo.

Transplantation of Cryopreserved Olfactory Ensheathing Cells Restores Loss of Functions in an Experimental Model

In the past decades, the properties of olfactory ensheathing cells (OECs) have been widely investigated. Studies have shown that transplantation of OECs cultured from the olfactory bulb mediates axonal regeneration, remyelination and restores lost functions in experimental central nervous system (CNS) injury models. Autologously sourcing the cells from the nasal mucosa or the olfactory bulb to treat patients with spinal cord injuries would be ideal, but the cell yield achieved may be inadequate to cover the surface area of the lesions typically encountered in human spinal cord contusion injuries. Therefore, banking allogenic cryopreserved olfactory bulb cells from donors or generating cell lines could provide a marked increase in cell stock available for transplantation. This study is undertaken in two control and two intervention groups. The control groups have lesions alone and lesions with collagen gel but without cells. The intervention groups have either transplantation of primary cultured olfactory bulb OECs (bOECs) encapsulated in collagen gel or cryopreserved bulb OECs (CbOECs) encapsulated in collagen gel. Here, we report that transplantation of cryopreserved rat bOECs encapsulated in collagen restored the loss of function in a vertical climbing test in a unilateral C6-T1 dorsal root injury model. The loss of function returns in 80% of rats with injuries in about 3 weeks comparable to that we observed after transplantation of primary cultured bOECs. The regeneration axons induced by the transplant are identified by neurofilament antibodies and ensheathed by OECs. Our results indicate that cryopreserved OECs retain their properties of inducing axon regeneration and restoring loss of function in the experimental model. This is a step forward to translate the research into future clinical applications.

Production of Germ Cell-Less Rainbow Trout by dead end Gene Knockout and their Use as Recipients for Germ Cell Transplantation

In germ cell transplantation experiments, the use of sterile recipients that do not produce their own gametes is an important prerequisite. Triploidization and dnd gene knockdown (KD) methods have been widely used to produce sterile fish. However, triploidization does not produce complete sterility in some fish species, and gene KD is labor and time intensive since it requires microinjection into individual fertilized eggs. To overcome these problems, in this study, we generated homozygous mutants of the dead end (dnd) gene in rainbow trout (Oncorhynchus mykiss) using the clustered regulatory interspaced short palindromic repeats/CRISPR-associated protein 9 (CRISPR/Cas9) system, analyzed their reproductive capacity, and evaluated their suitability as recipients for germ cell transplantation. By crossing F1 heterozygous mutants produced from founders subjected to genome editing, an F2 generation consisting of approximately 1/4 homozygous knockout mutants (dnd KO) was obtained. The dnd KO hatchlings retained the same number of primordial germ cells (PGCs) as the wild-type (WT) individuals, after which the number gradually decreased. At 1 year of age, germ cells were completely absent in all analyzed individuals. To evaluate the dnd KO individuals as recipients for germ cell transplantation, germ cells prepared from donor individuals were transplanted into the abdominal cavity of dnd KO hatchlings. These cells migrated to the recipient gonads, where they initiated gametogenesis. The mature recipient individuals produced only donor-derived sperm and eggs in equivalent numbers to WT rainbow trout. These results indicate that dnd KO rainbow trout are suitable recipient candidates possessing a high capacity to nurse donor-derived germ cells.

MERTK+/hi M2c Macrophages Induced by Baicalin Alleviate Non-Alcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is one of the most common liver diseases worldwide. An accumulation of fat, followed by inflammation, is the major cause of NAFLD progression. During inflammation, macrophages are the most abundant immune cells recruited to the site of injury. Macrophages are classified into "proinflammatory" M1 macrophages, and "anti-inflammatory" M2 macrophages. In NAFLD, M1 macrophages are the most prominent macrophages that lead to an excessive inflammatory response. Previously, we found that baicalin could polarize macrophages into anti-inflammatory M2c subtype macrophages with an increased level of MERTK expression. Several studies have also shown a strong correlation between MERTK expression and cholesterol efflux, efferocytosis, as well as phagocytosis capability. Therefore, in this study, we aim to elucidate the potential and efficacy of mononuclear-cell (MNC)-derived MERTK+/hi M2c macrophages induced by baicalin as a cell-based therapy for NAFLD treatment. In our results, we have demonstrated that a MERTK+/hi M2c macrophage injection to NAFLD mice contributes to an increased level of serum HDL secretion in the liver, a decline in the circulating CD4+CD25- and CD8+CD25- T cells and lowers the total NAFLD pathological score by lessening the inflammation, necrosis, and fibrosis. In the liver, profibrotic COL1A1 and FN, proinflammation TNFα, as well as the regulator of lipid metabolism PPARɣ expression, were also downregulated after injection. In parallel, the transcriptomic profiles of the injected MERTK+/hi M2c macrophages showed that the various genes directly or indirectly involved in NAFLD progression (e.g., SERPINE1, FADS2) were also suppressed. Downregulation of cytokines and inflammation-associated genes, such as CCR5, may promote a pro-resolving milieu in the NAFLD liver. Altogether, cell-based therapy using MERTK+/hi M2c macrophages is promising, as it ameliorates NAFLD in mice.

Application of Modified mRNA in Somatic Reprogramming to Pluripotency and Directed Conversion of Cell Fate

Modified mRNA (modRNA)-based somatic reprogramming is an effective and safe approach that overcomes the genomic mutation risk caused by viral integrative methods. It has improved the disadvantages of conventional mRNA and has better stability and immunogenicity. The modRNA molecules encoding multiple pluripotent factors have been applied successfully in reprogramming somatic cells such as fibroblasts, mesenchymal stem cells, and amniotic fluid stem cells to generate pluripotent stem cells (iPSCs). Moreover, it also can be directly used in the terminal differentiation of stem cells and fibroblasts into functional therapeutic cells, which exhibit great promise in disease modeling, drug screening, cell transplantation therapy, and regenerative medicine. In this review, we summarized the reprogramming applications of modified mRNA in iPSC generation and therapeutic applications of functionally differentiated cells.

Conditionally immortalised leukaemia initiating cells co-expressing Hoxa9/Meis1 demonstrate microenvironmental adaptation properties ex vivo while maintaining myelomonocytic memory

Regulation of haematopoietic stem cell fate through conditional gene expression could improve understanding of healthy haematopoietic and leukaemia initiating cell (LIC) biology. We established conditionally immortalised myeloid progenitor cell lines co-expressing constitutive Hoxa9.EGFP and inducible Meis1.dTomato (H9M-ciMP) to study growth behaviour, immunophenotype and morphology under different cytokine/microenvironmental conditions ex vivo upon doxycycline (DOX) induction or removal. The vector design and drug-dependent selection approach identified new retroviral insertion (RVI) sites that potentially collaborate with Meis1/Hoxa9 and define H9M-ciMP fate. For most cell lines, myelomonocytic conditions supported reversible H9M-ciMP differentiation into neutrophils and macrophages with DOX-dependent modulation of Hoxa9/Meis1 and CD11b/Gr-1 expression. Here, up-regulation of Meis1/Hoxa9 promoted reconstitution of exponential expansion of immature H9M-ciMPs after DOX reapplication. Stem cell maintaining conditions supported selective H9M-ciMP exponential growth. H9M-ciMPs that had Ninj2 RVI and were cultured under myelomonocytic or stem cell maintaining conditions revealed the development of DOX-dependent acute myeloid leukaemia in a murine transplantation model. Transcriptional dysregulation of Ninj2 and distal genes surrounding RVI (Rad52, Kdm5a) was detected. All studied H9M-ciMPs demonstrated adaptation to T-lymphoid microenvironmental conditions while maintaining immature myelomonocytic features. Thus, the established system is relevant to leukaemia and stem cell biology.

Transplantation of olfactory ensheathing cells promotes the therapeutic effect of neural stem cells on spinal cord injury by inhibiting necrioptosis

Transplantation of neural stem cells (NSCs) is one of the most promising treatments for spinal cord injury (SCI). However, the limited survival of transplanted NSCs reduces their therapeutic effects. The aim of the present study was to examine whether a co-transplantation of olfactory ensheathing cells (OECs) may enhance the survival of NSCs and improve the beneficial effects of NSCs in rats with SCI, as well as to investigate potential mechanisms underlying such efficacies. Co-transplantation of OECs and NSCs was used to treat rats with SCI. Sympathetic nerve function was determined by measuring sympathetic skin responses. The results showed that OEC/NSC co-transplantation improved motor function and autonomic nerve function in rats with SCI. Co-transplantation of OECs promoted NSC-induced neuroprotection and inhibited programmed necrosis of NSCs, which was mediated by receptor-interacting protein kinase 3 (RIP3) and mixed lineage kinase domain-like protein (MLKL). Furthermore, OECs increased the proliferation and differentiation of NSCs in vitro, and improved the survival rate of NSCs in vivo. Taken together, we conclude that transplantation of OECs inhibited programmed necrosis of co-transplanted NSCs to promote therapeutic effects on SCI. Therefore, co-transplantation of OECs and NSCs may represent a promising strategy for treating patients with SCI.

Strategies to Overcome the Barrier of Ischemic Microenvironment in Cell Therapy of Cardiovascular Disease

The transplantation of various immune cell types are promising approaches for the treatment of ischemic cardiovascular disease including myocardial infarction (MI) and peripheral arterial disease (PAD). Major limitation of these so-called Advanced Therapy Medicinal Products (ATMPs) is the ischemic microenvironment affecting cell homeostasis and limiting the demanded effect of the transplanted cell products. Accordingly, different clinical and experimental strategies have been evolved to overcome these obstacles. Here, we give a short review of the different experimental and clinical strategies to solve these issues due to ischemic cardiovascular disease.

CXCL10 encoding synNotch T cells enhance anti-tumor immune responses without systemic side effect

Modifying T cells to attack tumors using engineered chimeric receptors display powerful new therapeutic capabilities. Unfortunately, the effectiveness of therapeutic T cells is limited due to the inherent T cell responses: certain facets of endogenous response programs may be toxic, and the ability to overcome the immunosuppression in TME is deficient. Here we developed a Notch receptor based synNotch T cell platform that is able to response to target tumor cells and selectively lead to CXCL10 production. Further study showed that the administration of synNotch T cells significantly inhibited the tumor growth in a humanized murine model, accompanied by the increased infiltration of CD3+T cells and elevated level of CXCL10 and IFN-γ in the tumor site. A slightly increased level of CXCL10 and limited IFN-γ were found in the serum in mice received synNotch T cells, suggesting a high security of this treatment. Finally, we demonstrated that CXCL10 is sufficient and indispensable for the synNotch T cells induced anti-tumor effect. This study provided theoretical and experimental bases for the clinical implication of CXCL10 encoding synNotch T cells.

Cell Transplantation to Restore Lost Auditory Nerve Function is a Realistic Clinical Opportunity

Hearing is one of our most important means of communication. Disabling hearing loss (DHL) is a long-standing, unmet problem in medicine, and in many elderly people, it leads to social isolation, depression, and even dementia. Traditionally, major efforts to cure DHL have focused on hair cells (HCs). However, the auditory nerve is also important because it transmits electrical signals generated by HCs to the brainstem. Its function is critical for the success of cochlear implants as well as for future therapies for HC regeneration. Over the past two decades, cell transplantation has emerged as a promising therapeutic option for restoring lost auditory nerve function, and two independent studies on animal models show that cell transplantation can lead to functional recovery. In this article, we consider the approaches most likely to achieve success in the clinic. We conclude that the structure and biochemical integrity of the auditory nerve is critical and that it is important to preserve the remaining neural scaffold, and in particular the glial scar, for the functional integration of donor cells. To exploit the natural, autologous cell scaffold and to minimize the deleterious effects of surgery, donor cells can be placed relatively easily on the surface of the nerve endoscopically. In this context, the selection of donor cells is a critical issue. Nevertheless, there is now a very realistic possibility for clinical application of cell transplantation for several different types of hearing loss.

Patient and public perspectives on cell and gene therapies: a systematic review

Cell and gene therapies offer opportunities for treating disease with potential to restore function, and cure disease. However, they are not without risk and pose complex logistical, economic, ethical and social challenges for health systems. Here we report our systematic review of the current evidence on patient and public knowledge and perspectives of cell and gene therapies, to inform future research, education and awareness raising activities. We screened 10,735 titles and abstracts, and evaluated the full texts of 151 publications. The final selection was 35 publications. Four themes were generated from the narrative synthesis of the study findings namely: (1) Knowledge and understanding of cell and gene therapies, (2) Acceptance of cell and gene therapies (3) Understanding of risk and benefits of therapy, and (4) Information needs and current sources of information. As potential funders or future recipients, it is important that the public and patients are aware of these therapies, understand the issues involved, and can contribute to the debate. This review highlights the need for appropriate patient and public education on the various aspects of cell and gene therapies. High quality studies exploring patient and public opinions and experiences of cell and gene therapy are required. Patient and public perceptions of these therapies, alongside evidence of clinical and cost-effectiveness, will be central to their uptake and use.

Improved engraftment of human peripheral blood mononuclear cells in NOG MHC double knockout mice generated using CRISPR/Cas9

Humanized mice are widely used to study the human immune system in vivo and develop therapies for various human diseases. Human peripheral blood mononuclear cells (PBMC)-engrafted NOD/Shi-scid IL2rγ^null (NOG) mice are useful models for characterization of human T cells. However, the development of graft-versus-host disease (GVHD) limits the use of NOG PBMC models. We previously established a NOG-major histocompatibility complex class I/II double knockout (dKO) mouse model. Although humanized dKO mice do not develop severe GVHD, they have impaired reproductive performance and reduced chimerism of human cells. In this study, we established a novel beta-2 microglobulin (B2m) KO mouse model using CRISPR/Cas9. By crossing B2m KO mice with I-Ab KO mice, we established a modified dKO (dKO-em) mouse model. Reproductivity was slightly improved in dKO-em mice, compared with conventional dKO (dKO-tm) mice. dKO-em mice showed no signs of GVHD after the transfer of human PBMCs; they also exhibited high engraftment efficiency. Engrafted human PBMCs survived significantly longer in the peripheral blood and spleens of dKO-em mice, compared with dKO-tm mice. In conclusion, dKO-em mice might constitute a promising PBMC-based humanized mouse model for the development and preclinical testing of novel therapeutics for human diseases.

μ-Lat: A mouse model to evaluate human immunodeficiency virus eradication strategies

A critical barrier to the development of a human immunodeficiency virus (HIV) cure is the lack of a scalable animal model that enables robust evaluation of eradication approaches prior to testing in humans. We established a humanized mouse model of latent HIV infection by transplanting "J-Lat" cells, Jurkat cells harboring a latent HIV provirus encoding an enhanced green fluorescent protein (GFP) reporter, into irradiated adult NOD.Cg-Prkdcscid Il2rgtm1Wjl /SzJ (NSG) mice. J-Lat cells exhibited successful engraftment in several tissues including spleen, bone barrow, peripheral blood, and lung, in line with the diverse natural tissue tropism of HIV. Administration of tumor necrosis factor (TNF)-α, an established HIV latency reversal agent, significantly induced GFP expression in engrafted cells across tissues, reflecting viral reactivation. These data suggest that our murine latency ("μ-Lat") model enables efficient determination of how effectively viral eradication agents, including latency reversal agents, penetrate, and function in diverse anatomical sites harboring HIV in vivo.

Single-cell lineage tracing approaches in hematology research: technical considerations

The coordinated differentiation of hematopoietic stem and progenitor cells (HSPCs) into the various mature blood cell types is responsible for sustaining blood and immune system homeostasis. The cell fate decisions underlying this important biological process are made at the level of single cells. Methods to trace the fate of single cells are therefore essential for understanding hematopoietic system activity in health and disease and have had a major impact on how we understand and represent hematopoiesis. Here, we discuss the basic methodologies and technical considerations for three important clonal assays: single-cell transplantation, lentiviral barcoding, and Sleeping Beauty barcoding. This perspective is a synthesis of presentations and discussions from the 2019 International Society for Experimental Hematology (ISEH) Annual Meeting New Investigator Technology Session and the 2019 ISEH Winter Webinar.

Combination of In Situ Lcn2 pRNA-RNAi Nanotherapeutics and iNSC Transplantation Ameliorates Experimental SCI in Mice

Spinal cord injury (SCI) is a debilitating neurological condition characterized by different cellular and molecular mechanisms that interplay in exacerbating the progression of the pathology. No fully restorative therapies are yet available, and it is thus becoming recognized that combinatorial approaches aimed at addressing different aspects of SCI will likely results in greater functional outcomes. Here we employed packaging RNA-mediated RNA interference (pRNA-RNAi) nanotherapeutics to downregulate in situ the expression of lipocalin 2 (Lcn2), a known mediator of neuroinflammation and autocrine mediator of reactive astrogliosis, and to create a more amenable niche for the subsequent transplantation of induced neural stem cells (iNSCs). To our knowledge, this is the first approach that takes advantage of the modular and multifunctional pRNA three-way junction platform in the SCI niche, while also exploiting the therapeutic potential of immune-compatible and feasible iNSC transplants. We show the combination of such treatments in a mouse model of contusion thoracic SCI leads to significant improvement of locomotor function, albeit not better than single pRNA-RNAi treatment, and results in synergistic histopathological effects, such as reduction of glial scar volume, diminished pro-inflammatory response, and promotion of neuronal survival. Our results provide evidence for a novel combinatorial approach for treating SCI.

Therapeutic Strategies for Duchenne Muscular Dystrophy: An Update

Neuromuscular disorders encompass a heterogeneous group of conditions that impair the function of muscles, motor neurons, peripheral nerves, and neuromuscular junctions. Being the most common and most severe type of muscular dystrophy, Duchenne muscular dystrophy (DMD), is caused by mutations in the X-linked dystrophin gene. Loss of dystrophin protein leads to recurrent myofiber damage, chronic inflammation, progressive fibrosis, and dysfunction of muscle stem cells. Over the last few years, there has been considerable development of diagnosis and therapeutics for DMD, but current treatments do not cure the disease. Here, we review the current status of DMD pathogenesis and therapy, focusing on mutational spectrum, diagnosis tools, clinical trials, and therapeutic approaches including dystrophin restoration, gene therapy, and myogenic cell transplantation. Furthermore, we present the clinical potential of advanced strategies combining gene editing, cell-based therapy with tissue engineering for the treatment of muscular dystrophy.

A pilot multi-centre prospective randomised controlled trial of RECELL for the treatment of venous leg ulcers

Venous leg ulcers (VLUs) have a significant impact on approximately 3% of the adult population worldwide, with a mean NHS wound care cost of £7600 per VLU over 12 months. The standard care for VLUs is compression therapy, with a significant number of ulcers failing to heal with this treatment, especially with wound size being a risk factor for non-healing. This multicentre, prospective, randomised trial evaluated the safety and effectiveness of autologous skin cell suspension (ASCS) combined with compression therapy compared with standard compression alone (Control) for the treatment of VLUs. Incidence of complete wound closure at 14 weeks, donor site closure, pain, Health-Related Quality of Life (HRQoL), satisfaction, and safety were assessed in 52 patients. At Week 14, VLUs treated with ASCS + compression had a statistically greater decrease in ulcer area compared with the Control (8.94 cm2 versus 1.23 cm2 , P = .0143). This finding was largely driven by ulcers >10 to 80 cm2 in size, as these ulcers had a higher mean percentage of reepithelialization at 14 weeks (ASCS + compression: 69.97% and Control: 11.07%, P = .0480). Additionally, subjects treated with ASCS + compression experienced a decrease in pain and an increase in HRQoL compared with the Control. This study indicates that application of ASCS + compression accelerates healing in large venous ulcers.

Advances in regenerative medicine for otolaryngology/head and neck surgery

Head and neck structures govern the vital functions of breathing and swallowing. Additionally, these structures facilitate our sense of self through vocal communication, hearing, facial animation, and physical appearance. Loss of these functions can lead to loss of life or greatly affect quality of life. Regenerative medicine is a rapidly developing field that aims to repair or replace damaged cells, tissues, and organs. Although the field is largely in its nascence, regenerative medicine holds promise for improving on conventional treatments for head and neck disorders or providing therapies where no current standard exists. This review presents milestones in the research of regenerative medicine in head and neck surgery.

Glycine Enhances Satellite Cell Proliferation, Cell Transplantation, and Oligonucleotide Efficacy in Dystrophic Muscle

The need to distribute therapy evenly systemically throughout the large muscle volume within the body makes Duchenne muscular dystrophy (DMD) therapy a challenge. Cell and exon-skipping therapies are promising but have limited effects, and thus enhancing their therapeutic potency is of paramount importance to increase the accessibility of these therapies to DMD patients. In this study, we demonstrate that co-administered glycine improves phosphorodiamidate morpholino oligomer (PMO) potency in mdx mice with marked functional improvement and an up to 50-fold increase of dystrophin in abdominal muscles compared to PMO in saline. Glycine boosts satellite cell proliferation and muscle regeneration by increasing activation of mammalian target of rapamycin complex 1 (mTORC1) and replenishing the one-carbon unit pool. The expanded regenerating myofiber population then results in increased PMO uptake. Glycine also augments the transplantation efficiency of exogenous satellite cells and primary myoblasts in mdx mice. Our data provide evidence that glycine enhances satellite cell proliferation, cell transplantation, and oligonucleotide efficacy in mdx mice, and thus it has therapeutic utility for cell therapy and drug delivery in muscle-wasting diseases.

Injectable Cardiac Cell Microdroplets for Tissue Regeneration

One of the strategies for heart regeneration includes cell delivery to the defected heart. However, most of the injected cells do not form quick cell-cell or cell-matrix interactions, therefore, their ability to engraft at the desired site and improve heart function is poor. Here, the use of a microfluidic system is reported for generating personalized hydrogel-based cellular microdroplets for cardiac cell delivery. To evaluate the system's limitations, a mathematical model of oxygen diffusion and consumption within the droplet is developed. Following, the microfluidic system's parameters are optimized and cardiac cells from neonatal rats or induced pluripotent stem cells are encapsulated. The morphology and cardiac specific markers are assessed and cell function within the droplets is analyzed. Finally, the cellular droplets are injected to mouse gastrocnemius muscle to validate cell retention, survival, and maturation within the host tissue. These results demonstrate the potential of this approach to generate personalized cellular microtissues, which can be injected to distinct regions in the body for treating damaged tissues.

Cell transplantation of retinal ganglion cells derived from hESCs

BACKGROUND

Glaucoma, the number one cause of irreversible blindness, is characterized by the loss of retinal ganglion cells (RGCs), which do not regenerate in humans or mammals after cell death. Cell transplantation provides an opportunity to restore vision in glaucoma, or other optic neuropathies. Since transplanting primary RGCs from deceased donor tissues may not be feasible, stem cell-derived RGCs could provide a plausible alternative source of donor cells for transplant.

OBJECTIVE

We define a robust chemically defined protocol to differentiate human embryonic stem cells (hESCs) into RGC-like neurons.

METHODS

Human embryonic stem cell lines (H7-A81 and H9) and induced pluripotent stem cell (iPSC) were used for RGC differentiation. RGC immaturity was measured by calcium imaging against muscimol. Cell markers were detected by immunofluorescence staining and qRT-PCR. RGC-like cells were intravitreally injected to rat eye, and co-stained with RBPMS and human nuclei markers. All experiments were conducted at least three times independently. Data were analyzed by ANOVA with Tukey's test with P value of <0.05 considered statistically significant.

RESULTS

We detected retinal progenitor markers Rx and Pax6 after 15 days of differentiation, and the expression of markers for RGC-specific differentiation (Brn3a and Brn3b), maturation (synaptophysin) and neurite growth (β-III-Tubulin) after an additional 15 days. We further examined the physiologic differentiation of these hESC-derived RGC-like progeny to those differentiated in vitro from primary rodent retinal progenitor cells (RPCs) with calcium imaging, and found that both populations demonstrate the immature RGC-like response to muscimol, a GABAA receptor agonist. By one week after transplant to the adult rat eye by intravitreal injection, the human RGC-like cells successfully migrated into the ganglion cell layer.

CONCLUSIONS

Our protocol provides a novel, short, and cost-effective approach for RGC differentiation from hESCs, and may broaden the scope for cell replacement therapy in RGC-related optic neuropathies such as glaucoma.

The application of iPSCs in Parkinson's disease

The discovery and application of induced pluripotent stem cells (iPSCs) provide a novel treatment modality for diseases, which remain incurable. Particularly, in the treatment of neurodegenerative diseases such as Parkinson's disease (PD), iPSC‑technology holds an interesting prospect for replacement therapy. Currently, the prognostic improvement of PD is limited and relies on symptomatic treatment. However, the symptomatic dopamine‑replacement therapies lose their long‑duration responses, and novel regenerative treatment modalities are needed. Animal models have provided valuable information and identified pathogenic mechanisms underlying PD but the lack of models that recapitulate the complex pathophysiology of the disease postpones further development of novel therapeutics. This review summarizes the possible uses of iPSCs in PD and discusses the future investigations needed for iPSCs as a possible treatment of PD patients.

Transplantation of sh-miR-199a-5p-Modified Olfactory Ensheathing Cells Promotes the Functional Recovery in Rats with Contusive Spinal Cord Injury

MicroRNAs (miRNAs) function as gene expression switches, and participate in diverse pathophysiological processes of spinal cord injury (SCI). Olfactory ensheathing cells (OECs) can alleviate pathological injury and facilitate functional recovery after SCI. However, the mechanisms by which OECs restore function are not well understood. This study aims to determine whether silencing miR-199a-5p would enhance the beneficial effects of the OECs. In this study, we measured miR-199a-5p levels in rat spinal cords with and without injury, with and without OEC transplants. Then, we transfected OECs with the sh-miR-199a-5p lentiviral vector to reduce miR-199a-5p expression and determined the effects of these OECs in SCI rats by Basso-Beattie-Bresnahan (BBB) locomotor scores, diffusion tensor imaging (DTI), and histological methods. We used western blotting to measure protein levels of Slit1, Robo2, and srGAP2. Finally, we used the dual-luciferase reporter assay to assess the relationship between miR-199-5p and Slit1, Robo2, and srGAP2 expression. We found that SCI significantly increased miR-199a-5p levels (P < 0.05), and OEC transplants significantly reduced miR-199a-5p expression (P < 0.05). Knockdown of miR-199a-5p in OECs had a better therapeutic effect on SCI rats, indicated by higher BBB scores and fractional anisotropy values on DTI, as well as histological findings. Reducing miR-199a-5p levels in transplanted OECs markedly increased spinal cord protein levels of Slit1, Robo2, and srGAP2. Our results demonstrated that transplantation of sh-miR-199a-5p-modified OECs promoted functional recovery in SCI rats, suggesting that miR-199a-5p knockdown was more beneficial to the therapeutic effects of OEC transplants. These findings provided new insights into miRNAs-mediated therapeutic mechanisms of OECs, which helps us to develop therapeutic strategies based on miRNAs and optimize cell therapy for SCI.

Phenotypic and Functional Characterization of Müller Glia Isolated from Induced Pluripotent Stem Cell-Derived Retinal Organoids: Improvement of Retinal Ganglion Cell Function upon Transplantation

Glaucoma is one of the leading causes of blindness, and there is an ongoing need for new therapies. Recent studies indicate that cell transplantation using Müller glia may be beneficial, but there is a need for novel sources of cells to provide therapeutic benefit. In this study, we have isolated Müller glia from retinal organoids formed by human induced pluripotent stem cells (hiPSCs) in vitro and have shown their ability to partially restore visual function in rats depleted of retinal ganglion cells by NMDA. Based on the present results, we suggest that Müller glia derived from retinal organoids formed by hiPSC may provide an attractive source of cells for human retinal therapies, to prevent and treat vision loss caused by retinal degenerative conditions. Stem Cells Translational Medicine 2019;8:775&784.

Elimination of donor CD47 protects against vascularized allograft rejection in mice

CD47 is a ubiquitously expressed transmembrane glycoprotein that plays a complex role in regulation of cell survival and function. We have previously shown that the interspecies incompatibility of CD47 plays an important role in triggering rejection of cellular xenografts by macrophages. However, the role of CD47 in solid organ transplantation remains undetermined. Here, we explored this question in mouse models of heart allotransplantation. We observed that the lack of CD47 in donor hearts had no deleterious effect on graft survival in syngeneic or single MHC class I-mismatched recipients, in which both wild-type (WT) and CD47 knockout (CD47 KO) mouse hearts survived long term with no sign of rejection. Paradoxically, elimination of donor CD47 was beneficial for graft survival in signal MHC class II- and class I- plus class II-mismatched combinations, in which CD47 KO donor hearts showed significantly improved survival compared to WT donor hearts. Similarly, CD47 KO donor hearts were more resistant than WT hearts to humoral rejection in α1,3-galactosyltransferase-deficient mice. Moreover, a significant prolongation of WT allografts was observed in recipient mice treated with antibodies against a CD47 ligand thrombospondin-1 (TSP1) or with TSP1 deficiency, indicating that TSP1-CD47 signaling may stimulate vascularized allograft rejection. Thus, unlike cellular transplantation, donor CD47 expression may accelerate the rejection of vascularized allografts.

Cardiac Extracellular Matrix Modification as a Therapeutic Approach

The cardiac extracellular matrix (cECM) is comprised of proteins and polysaccharides secreted by cardiac cell types, which provide structural and biochemical support to cardiovascular tissue. The roles of cECM proteins and the associated family of cell surface receptor, integrins, have been explored in vivo via the generation of knockout experimental animal models. However, the complexity of tissues makes it difficult to isolate the effects of individual cECM proteins on a particular cell process or disease state. The desire to further dissect the role of cECM has led to the development of a variety of in vitro model systems, which are now being used not only for basic studies but also for testing drug efficacy and toxicity and for generating therapeutic scaffolds. These systems began with 2D coatings of cECM derived from tissue and have developed to include recombinant ECM proteins, ECM fragments, and ECM mimics. Most recently 3D model systems have emerged, made possible by several developing technologies including, and most notably, 3D bioprinting. This chapter will attempt to track the evolution of our understanding of the relationship between cECM and cell behavior from in vivo model to in vitro control systems. We end the chapter with a summary of how basic studies such as these have informed the use of cECM as a direct therapy.

Germ Cell Transplantation in Avian Species

Germ cell transplantation technology has played a critical role in germline modification and preservation of genetic resources. Several germ cell transplantation systems have been developed, including sperm, oocyte, or germline stem cell transplantation systems in mammals. Meanwhile, in avian species, this has mostly relied on primordial germ cell (PGC) transplantation for efficient germline transmission. In this chapter, we describe how to isolate PGCs from avian embryos and produce germline chimeras through transplantation of donor PGCs to recipient embryos.

Cell Transplantation as a Method to Investigate Spinal Cord Regeneration in Regenerative and Nonregenerative Xenopus Stages

Mammals are not capable of regenerating their central nervous system (CNS); anamniotes, however, can regenerate in response to injury. The mechanisms that explain the different regenerative capabilities include: (i) extrinsic mechanisms that consider the cellular environment and extracellular matrix composition, (ii) intrinsic factors implicating the presence or absence of genetic programs that promote axon regeneration, and (iii) the presence or absence of neural stem and progenitors cells (NSPCs) that allow neurogenesis. Xenopus laevis is able to regenerate its CNS during larval stages (i.e., the regenerative stage [R-stage]). However, concomitant with metamorphosis this capacity decreases and is lost completely in juvenile froglets (i.e., nonregenerative stages [NR-stages]). The loss of the regenerative ability correlates with a reduction in the percentage of Sox2⁺ cells, which are putative NSPCs. This protocol shows the effect of transplantation of spinal cord cells from R-stage Xenopus larvae into NR-stage froglets. Using this procedure, it is possible to study axon regeneration and stem cell biology in vivo.

Interspecific germ cell transplantation: a new light in the conservation of valuable Balkan trout genetic resources?

Interspecific transplantation of germ cells from the brown trout Salmo trutta m. fario and the European grayling Thymallus thymallus into rainbow trout Oncorhynchus mykiss recipients was carried out in order to improve current practices in conservation of genetic resources of endangered salmonid species in the Balkan Peninsula. Current conservation methods mainly include in situ efforts such as the maintenance of purebred individuals in isolated streams and restocking with purebred fingerlings; however, additional ex situ strategies such as surrogate production are needed. Steps required for transplantation such as isolation of high number of viable germ cells and fluorescent labeling of germ cells which are to be transplanted have been optimized. Isolated and labeled brown trout and grayling germ cells were intraperitoneally transplanted into 3 to 5 days post hatch rainbow trout larvae. Survival of the injected larvae was comparable to the controls. Sixty days after transplantation, fluorescently labeled donor cells were detected within the recipient gonads indicating successful incorporation of germ cells (brown trout spermatogonia and oogonia-27%; grayling spermatogonia-28%; grayling oogonia-23%). PCR amplification of donor mtDNA CR fragments within the recipient gonads additionally corroborated the success of incorporation. Overall, the transplantation method demonstrated in this study presents the first step and a possible onset of the application of the germ cell transplantation technology in conservation and revitalization of genetic resources of endangered and endemic species or populations of salmonid fish and thus give rise to new or improved management strategies for such species.

A phase IIb, randomised, double-blind, placebo-controlled, dose-ranging investigation of the safety and efficacy of NTCELL® [immunoprotected (alginate-encapsulated) porcine choroid plexus cells for xenotransplantation] in patients with Parkinson's disease

INTRODUCTION

Regenerative therapies in Parkinson's disease aim to slow neurodegeneration and re-establish damaged neuronal circuitry. Neurotrophins are potent endogenous regulators of neuronal survival, development and regeneration. They represent an attractive regenerative treatment option in Parkinson's disease. Porcine choroid plexus produces a number of neurotrophins, and can be safely delivered to the striatum in an encapsulated formulation (termed NTCELL^®) to protect them from immune attack. NTCELL^® has shown regenerative potential in animal models of stroke, Huntington's disease and Parkinson's disease. Following promising results from an initial open label safety study of intra-striatal delivery of NTCELL^® in human subjects, we sought to specifically investigate the safety and efficacy of NTCELL^® for the treatment of Parkinson's disease.

METHODS

18 patients aged 56-65 years with idiopathic Parkinson's disease of at least 5 years duration were randomised to receive either sham surgery (general anaesthesia and partial thickness burr holes) or intra-striatal delivery of NTCELL^® (the 3 groups in the treatment arm receiving incremental NTCELL^® doses).

RESULTS

At 26 weeks, we found no significant difference in total UPDRS scores ('on' and 'off'), UPDRS motor scores ('on' and 'off'), PDQ-39, UDysRS, timed walk or modified Hoehn and Yahr stage between patients implanted with NTCELL^® and patients undergoing sham procedure. There were no serious adverse events or xenogeneic viral transmission during the study.

CONCLUSION

The study did not meet its primary efficacy end-point of a change in UPDRS at 26 weeks post-intervention compared with baseline. Stereotactic NTCELL^® implantation was safe and well tolerated.

Evidence of axon connectivity across a spinal cord transection in rats treated with epidural stimulation and motor training combined with olfactory ensheathing cell transplantation

Olfactory ensheathing cells (OECs) are unique glia that support axon outgrowth in the olfactory system, and when used as cellular therapy after spinal cord injury, improve recovery and axon regeneration. Here we assessed the effects of combining OEC transplantation with another promising therapy, epidural electrical stimulation during a rehabilitative motor task. Sprague-Dawley rats received a mid-thoracic transection and transplantation of OECs or fibroblasts (FBs) followed by lumbar stimulation while climbing an inclined grid. We injected pseudorabies virus (PRV) into hindlimb muscles 7 months post-injury to assess connectivity across the transection. Analyses showed that the number of serotonergic (5-HT) axons that crossed the rostral scar border and the area of neurofilament-positive axons in the injury site were both greater in OEC- than FB-treated rats. We detected PRV-labeled cells rostral to the transection and remarkable evidence of 5-HT and PRV axons crossing the injury site in 1 OEC- and 1 FB-treated rat. The axons that crossed suggested either axon regeneration (OEC) or small areas of probable tissue sparing (FB). Most PRV-labeled thoracic neurons were detected in laminae VII or X, and ~25% expressed Chx10, a marker for V2a interneurons. These findings suggest potential regeneration or sparing of circuits that connect thoracic interneurons to lumbar somatic motor neurons. Despite evidence of axonal connectivity, no behavioral changes were detected in this small-scale study. Together these data suggest that when supplemented with epidural stimulation and climbing, OEC transplantation can increase axonal growth across the injury site and may promote recovery of propriospinal circuitry.

Hepatocyte-like cells generated by direct reprogramming from murine somatic cells can repopulate decellularized livers

Direct reprogramming represents an easy technique to generate induced hepatocytes (iHeps) from somatic cells. However, current protocols are accompanied by several drawbacks as iHeps are heterogenous and lack fully mature phenotypes of primary hepatocytes. Here, we established a polycistronic expression system to induce the direct reprogramming of mouse embryonic fibroblasts towards hepatocytes. The resulting iHeps are homogenous and display key properties of primary hepatocytes, such as expression of hepatocyte markers, albumin secretion, and presence of liver transaminases. iHeps also possess the capacity to repopulate decellularized liver tissue and exhibit enhanced hepatic maturation. As such, we present a novel strategy to generate homogenous and functional iHeps for applications in tissue engineering and cell therapy.

Future directions for therapeutic strategies in post-ischaemic vascularization: a position paper from European Society of Cardiology Working Group on Atherosclerosis and Vascular Biology

Modulation of vessel growth holds great promise for treatment of cardiovascular disease. Strategies to promote vascularization can potentially restore function in ischaemic tissues. On the other hand, plaque neovascularization has been shown to associate with vulnerable plaque phenotypes and adverse events. The current lack of clinical success in regulating vascularization illustrates the complexity of the vascularization process, which involves a delicate balance between pro- and anti-angiogenic regulators and effectors. This is compounded by limitations in the models used to study vascularization that do not reflect the eventual clinical target population. Nevertheless, there is a large body of evidence that validate the importance of angiogenesis as a therapeutic concept. The overall aim of this Position Paper of the ESC Working Group of Atherosclerosis and Vascular biology is to provide guidance for the next steps to be taken from pre-clinical studies on vascularization towards clinical application. To this end, the current state of knowledge in terms of therapeutic strategies for targeting vascularization in post-ischaemic disease is reviewed and discussed. A consensus statement is provided on how to optimize vascularization studies for the identification of suitable targets, the use of animal models of disease, and the analysis of novel delivery methods.

Correcting Nasojugal Groove with Autologous Cultured Fibroblast Injection: A Pilot Study

BACKGROUND

A new commercial drug that contains autologous cultured fibroblasts has been developed and approved by the United States Food and Drug Administration for improving the appearance of nasolabial folds. However, the treatment requires three sessions every 3-6 weeks. It is known that the skin overlying the nasojugal groove is thinner, and the wrinkle is generally shallower than nasolabial folds. Therefore, we hypothesized that the nasojugal groove could be improved by just one treatment session. Therefore, the purpose of this study was to evaluate the efficacy and safety of autologous cultured fibroblast injection to correct nasojugal grooves.

METHODS

Forty-six subjects with nasojugal grooves were enrolled in this study. They were injected with autologous cultured fibroblasts or placebo in one session. Blinded evaluators and subjects assessed the efficacy using a validated wrinkle assessment scale at 4, 12, and 24 weeks after the injection. Information of adverse events was collected at each visit.

RESULTS

Based on the evaluators' assessment at 24 weeks after the injection, 76% of subjects treated with autologous cultured fibroblasts showed improvement whereas 0% of subjects treated with placebo showed improvement (P < 0.0001). Based on self-assessment at 24 weeks after the injection, 72% of subjects treated with autologous cultured fibroblasts and 45% of subjects treated with placebo showed improvement (P = 0.0662). There were no serious adverse events related to autologous cultured fibroblast injection.

CONCLUSIONS

Autologous cultured fibroblast injection might be effective and safe to correct nasojugal grooves.

LEVEL OF EVIDENCE I

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Partial Recovery of Proprioception in Rats with Dorsal Root Injury after Human Olfactory Bulb Cell Transplantation

Transplanted human olfactory ensheathing cells (hOECs) were mixed with collagen into a unilateral transection of four dorsal roots (C6-T1) in a rat model. By mixing with collagen, the limited numbers of hOEC were maximized from an olfactory bulb biopsy and optimize cavity filling. Cyclosporine was administered daily to prevent immune rejection. Forelimb proprioception was assessed weekly in a vertical climb task. Half of the rats receiving hOEC transplants showed some functional improvement ("responders") over six weeks of the study while the other half did not ("nonresponders") and performed similarly to "injured only" rats. Transplanted cells were seen at both one week and six weeks after the surgical procedure; many were concentrated within the lesion cavity, but others were found with elongated processes in the overlying connective tissue. There were some fibers in the injury area associated with transplanted cells that were immunostained for neurofilament and TUJ1. Responder and nonresponder rats were compared with regard to microglial activation within the deep dorsal horn of cervical levels C7, C8 and also axon loss within the cuneate fasciculus at cervical level C3. Little difference was seen in microglial activation or axonal loss that could account for the improved proprioception in the responders group. This preliminary study is the first to transplant human olfactory bulb cells into a rat model of dorsal root injury; by refining each component part of the procedure, the repair potential of OECs can be maximized in a clinical setting.

Development of an in vitro potency assay for human skeletal muscle derived cells

BACKGROUND

Potency is a quantitative measure of the desired biological function of an advanced therapy medicinal product (ATMP) and is a prerequisite for market approval application (MAA). To assess the potency of human skeletal muscle-derived cells (SMDCs), which are currently investigated in clinical trials for the regeneration of skeletal muscle defects, we evaluated acetylcholinesterase (AChE), which is expressed in skeletal muscle and nervous tissue of all mammals.

METHODS

CD56+ SMDCs were separated from CD56- SMDCs by magnetic activated cell sorting (MACS) and both differentiated in skeletal muscle differentiation medium. AChE activity of in vitro differentiated SMDCs was correlated with CD56 expression, fusion index, cell number, cell doubling numbers, differentiation markers and compared to the clinical efficacy in patients treated with SMDCs against fecal incontinence.

RESULTS

CD56- SMDCs did not form multinucleated myotubes and remained low in AChE activity during differentiation. CD56+ SMDCs generated myotubes and increased in AChE activity during differentiation. AChE activity was found to accurately reflect the number of CD56+ SMDCs in culture, their fusion competence, and cell doubling number. In patients with fecal incontinence responding to SMDCs treatment, the improvement of clinical symptoms was positively linked with the AChE activity of the SMDCs injected.

DISCUSSION

AChE activity was found to truly reflect the in vitro differentiation status of SMDCs and to be superior to the mere use of surface markers as it reflects not only the number of myogenic SMDCs in culture but also their fusion competence and population doubling number, thus combining cell quality and quantification of the expected mode of action (MoA) of SMDCs. Moreover, the successful in vitro validation of the assay proves its suitability for routine use. Most convincingly, our results demonstrate a link between clinical efficacy and the AChE activity of the SMDCs preparations used for the treatment of fecal incontinence. Thus, we recommend using AChE activity of in vitro differentiated SMDCs as a potency measure in end stage (phase III) clinical trials using SMDCs for skeletal muscle regeneration and subsequent market approval application (MAA).

Next-generation pacemakers: from small devices to biological pacemakers

Electrogenesis in the heart begins in the sinoatrial node and proceeds down the conduction system to originate the heartbeat. Conduction system disorders lead to slow heart rates that are insufficient to support the circulation, necessitating implantation of electronic pacemakers. The typical electronic pacemaker consists of a subcutaneous generator and battery module attached to one or more endocardial leads. New leadless pacemakers can be implanted directly into the right ventricular apex, providing single-chamber pacing without a subcutaneous generator. Modern pacemakers are generally reliable, and their programmability provides options for different pacing modes tailored to specific clinical needs. Advances in device technology will probably include alternative energy sources and dual-chamber leadless pacing in the not-too-distant future. Although effective, current electronic devices have limitations related to lead or generator malfunction, lack of autonomic responsiveness, undesirable interactions with strong magnetic fields, and device-related infections. Biological pacemakers, generated by somatic gene transfer, cell fusion, or cell transplantation, provide an alternative to electronic devices. Somatic reprogramming strategies, which involve transfer of genes encoding transcription factors to transform working myocardium into a surrogate sinoatrial node, are furthest along in the translational pipeline. Even as electronic pacemakers become smaller and less invasive, biological pacemakers might expand the therapeutic armamentarium for conduction system disorders.

Investigation of a New Microcapsule Membrane Combining Alginate, Chitosan, Polyethylene Glycol and Poly-L-Lysine for Cell Transplantation Applications

Microencapsulation of living cells may serve as an alternative therapy for patients requiring organ transplants. One of the limiting factors in the progress of such therapy is attaining a biocompatible and mechanically stable polymer. The current study investigates the potential of a novel membrane combining alginate, chitosan, polyethylene glycol (PEG) and poly-L-lysine (PLL) with the objective of proposing a membrane suitable for cell entrapment that may overcome some of the shortcomings of the widely studied alginate-poly-L-lysine-alginate (APA) capsules. The novel microcapsule was formulated using a 1.5% alginate solution coated with 0.05% chitosan, 0.1% PEG and 0.05% poly-L-lysine with a final layer of 0.1% alginate. Microcapsules having a diameter of 450 ± 30 μm were prepared. Upon citrate treatment, the membrane remained intact and retained its spherical structure. The membrane was able to support liver cell proliferation and the encapsulated cells were capable of secreting proteins. The study demonstrated that the new membrane can be used for cell entrapment. However, further investigations are needed to assess its potential for long term transplantation and usage in the development of bioartificial organs.

Clonal Analysis of Planarian Stem Cells by Subtotal Irradiation and Single-Cell Transplantation

Stem cells, which both self-renew and produce differentiated progeny, represent fundamental biological units for the development, growth, maintenance, and regeneration of adult tissues. Characterization of stem cell lineage potential can be accomplished with clonal assays that interrogate stem cell output at the single-cell level. Here we present two methods for clonal analysis of individual proliferative cells (neoblasts) in the planarian Schmidtea mediterranea. The first method utilizes "subtotal" gamma irradiation to study rare surviving neoblasts and their clonal descendants in their native environment. The second method utilizes a fluorescent-activated cell sorting (FACS) strategy to obtain neoblast-enriched cell fractions, followed by single-cell transplantation into lethally irradiated hosts. Together, these methods provide a framework for generation and analysis of stem cell-derived clones in planarians.

Human heterologous liver cells transiently improve hyperammonemia and ureagenesis in individuals with severe urea cycle disorders

BACKGROUND

Urea cycle disorders (UCDs) still have a poor prognosis despite several therapeutic advancements. As liver transplantation can provide a cure, liver cell therapy (LCT) might be a new therapeutic option in these patients.

METHODS

Twelve patients with severe UCDs were included in this prospective clinical trial. Patients received up to six infusions of cryopreserved human heterologous liver cells via a surgically placed catheter in the portal vein. Portal vein pressure, portal vein flow, and vital signs were monitored continuously. Calcineurin inhibitors and steroids were used for immunosuppression. In four patients, ureagenesis was determined with stable isotopes. Number and severity of hyperammonemic events and side effects of immunosuppression were analyzed during an observation period of up to 2 years.

RESULTS

No study-related mortality was observed. The application catheter dislocated in two children. No significant side effects of catheter application or cell infusion were noted in the other ten patients. The overall incidence of infections did not differ significantly from a historical control group, and no specific side effects of immunosuppression were found. Seven patients were treated per protocol and could be analyzed for efficacy. Severe metabolic crises could be prevented in all of these patients, moderate crises in four of seven. Ureagenesis increased after cell infusion in all patients investigated.

CONCLUSIONS

We found a favorable safety profile with respect to catheter placement, intraportal liver cell infusion, and immunosuppression. More than half of the children treated per protocol experienced metabolic stabilization and could be safely bridged to liver transplantation.

Hydrogel biomaterials and their therapeutic potential for muscle injuries and muscular dystrophies

Muscular diseases such as muscular dystrophies and muscle injuries constitute a large group of ailments that manifest as muscle weakness, atrophy or fibrosis. Although cell therapy is a promising treatment option, the delivery and retention of cells in the muscle is difficult and prevents sustained regeneration needed for adequate functional improvements. Various types of biomaterials with different physical and chemical properties have been developed to improve the delivery of cells and/or growth factors for treating muscle injuries. Hydrogels are a family of materials with distinct advantages for use as cell delivery systems in muscle injuries and ailments, including their mild processing conditions, their similarities to natural tissue extracellular matrix, and their ability to be delivered with less invasive approaches. Moreover, hydrogels can be made to completely degrade in the body, leaving behind their biological payload in a process that can enhance the therapeutic process. For these reasons, hydrogels have shown great potential as cell delivery matrices. This paper reviews a few of the hydrogel systems currently being applied together with cell therapy and/or growth factor delivery to promote the therapeutic repair of muscle injuries and muscle wasting diseases such as muscular dystrophies.

In vivo transplantation of 3D encapsulated ovarian constructs in rats corrects abnormalities of ovarian failure

Safe clinical hormone replacement (HR) will likely become increasingly important in the growing populations of aged women and cancer patients undergoing treatments that ablate the ovaries. Cell-based HRT (cHRT) is an alternative approach that may allow certain physiological outcomes to be achieved with lower circulating hormone levels than pharmacological means due to participation of cells in the hypothalamus-pituitary-ovary feedback control loop. Here we describe the in vivo performance of 3D bioengineered ovarian constructs that recapitulate native cell-cell interactions between ovarian granulosa and theca cells as an approach to cHRT. The constructs are fabricated using either Ca++ or Sr++ to crosslink alginate. Following implantation in ovariectomized (ovx) rats, the Sr++-cross-linked constructs achieve stable secretion of hormones during 90 days of study. Further, we show these constructs with isogeneic cells to be effective in ameliorating adverse effects of hormone deficiency, including bone health, uterine health, and body composition in this rat model.

Concise Review: Developing Best-Practice Models for the Therapeutic Use of Extracellular Vesicles

Growing interest in extracellular vesicles (EVs, including exosomes and microvesicles) as therapeutic entities, particularly in stem cell-related approaches, has underlined the need for standardization and coordination of development efforts. Members of the International Society for Extracellular Vesicles and the Society for Clinical Research and Translation of Extracellular Vesicles Singapore convened a Workshop on this topic to discuss the opportunities and challenges associated with development of EV-based therapeutics at the preclinical and clinical levels. This review outlines topic-specific action items that, if addressed, will enhance the development of best-practice models for EV therapies. Stem Cells Translational Medicine 2017;6:1730-1739.