Cell Type For Transplantation Research Articles

Cell Therapy for Neurological Disorders: The Perspective of Promising Cells.

Simple SummaryCell therapy has become a powerful method for regenerative medicine. However, there has not been an ideal cell type and cell source for the treatment of neurological diseases such as Parkinson’s disease and Alzheimer’s disease. This review aims to introduce the potentials of different cells for treating neurological disorders by collecting the results from related clinical trials and recent animal studies. It is an overview of some promising cells that may be clinically used for neurological disorders. The characteristics of each cell type and the main mechanism of function are also described.Neurological disorders are big public health challenges that are afflicting hundreds of millions of people around the world. Although many conventional pharmacological therapies have been tested in patients, their therapeutic efficacies to alleviate their symptoms and slow down the course of the diseases are usually limited. Cell therapy has attracted the interest of many researchers in the last several decades and has brought new hope for treating neurological disorders. Moreover, numerous studies have shown promising results. However, none of the studies has led to a promising therapy for patients with neurological disorders, despite the ongoing and completed clinical trials. There are many factors that may affect the outcome of cell therapy for neurological disorders due to the complexity of the nervous system, especially cell types for transplantation and the specific disease for treatment. This paper provides a review of the various cell types from humans that may be clinically used for neurological disorders, based on their characteristics and current progress in related studies.

Role of Stem Cells in Treatment of Sensorineural Hearing Loss

Abstract Background More than 5% of the world population lives with a hearing impairment. The main factors responsible for hearing degeneration are ototoxic drugs, aging, continued exposure to excessive noise and infections. The pool of adult stem cells in the inner ear drops dramatically after birth, and therefore an endogenous cellular source for regeneration is absent. Objectives The purpose of this study is to evaluate the role of mesenchymal stem cells in the treatment of severe to profound sensorineural hearing loss as regarding permanent regeneration of the auditory hair cells. Materials and Methods It is a prospective study which was performed in the period of May 2019 till December 2019 and encountered 40 adult male guinea pigs, aged 6 to 8 weeks (body weight 250-500 gram). 30 guinea pigs had been subjected to right side intratympanic injection of Garamycin sulphate to induce sensorineural hearing loss then the 30 animals were subdivided after that into 2 groups; Group A (15 animals) were treated by mesenchymal stem cells implantation in right inner ear cochlea and group B (15 animals) left untreated and the remaining 10 guinea pigs; Group C left normally as a control group. Results As respect to histopathological examination, 100% of animals in group B (n = 15) expressed severe degenerative changes in the peripheral organs. The outer hair cells showed severe destruction with individual loss of the inner hair cells. Also the supporting cells of Corti’s organ presented severe necrosis which was more relevant in the basal turns. We used the bone marrow differentiated MSCs to evaluate their potency in regeneration of the damaged and lost sensorineural elements in gentamicin injured cochlea. In group A (n = 15) 9 out of 15 (60%) expressed profound regeneration and 4 out of 15 (26.66%) expressed early regenerative changes, while 2 animals (13.33%) expressed less degenerative changes which impacted by gentamicin. Conclusion Stem cell transplantation is a promising approach for hearing loss therapy. The choice of stem cell type for transplantation plays a crucial role in the outcome. MSCs are multipotent cells that can be isolated from adult bone marrow and can be induced to differentiate into a variety of tissues in vitro and in vivo.

Targeted Liquid Biopsy Using Irradiation to Facilitate the Release of Cell-Free DNA from a Spatially Aimed Tumor Tissue.

PurposeWe investigated the feasibility of using an anatomically localized, target-enriched liquid biopsy (TLB) in mouse models of lung cancer.Materials and MethodsAfter irradiating xenograft mouse with human lung cancer cell lines, H1299 (NRAS proto-oncogene, GTPase [NRAS] Q61K) and HCC827 (epidermal growth factor receptor [EGFR] E746–750del), circulating (cell-free) tumor DNA (ctDNA) levels were monitored with quantitative polymerase chain reaction on human long interspersed nuclear element-1 and cell line-specific mutations. We checked dose-dependency at 6, 12, or 18 Gy to each tumor-bearing mouse leg using 6-MV photon beams. We also analyzed ctDNA of lung cancer patients by LiquidSCAN, a targeted deep sequencing to validated the clinical performances of TLB method.ResultsIrradiation could enhance the detection sensitivity of NRAS Q61K in the plasma sample of H1299-xenograft mouse to 4.5-fold. While cell-free DNA (cfDNA) level was not changed at 6 Gy, ctDNA level was increased upon irradiation. Using double-xenograft mouse with H1299 and HCC827, ctDNA polymerase chain reaction analysis with local irradiation in each region could specify mutation type matched to transplanted cell types, proposing an anatomically localized, TLB. Furthermore, when we performed targeted deep sequencing of cfDNA to monitor ctDNA level in 11 patients with lung cancer who underwent radiotherapy, the average ctDNA level was increased within a week after the start of radiotherapy.ConclusionTLB using irradiation could temporarily amplify ctDNA release in xenograft mouse and lung cancer patients, which enables us to develop theragnostic method for cancer patients with accurate ctDNA detection.

Expanded potential stem cell media as a tool to study human developmental hematopoiesis in vitro

Pluripotent stem cell (PSC) differentiation in vitro represents a powerful and tractable model to study mammalian development and an unlimited source of cells for regenerative medicine. Within hematology, in vitro PSC hematopoiesis affords novel insights into blood formation and represents an exciting potential approach to generate hematopoietic and immune cell types for transplantation and transfusion. Most studies to date have focused on in vitro hematopoiesis from mouse PSCs and human PSCs. However, differences in mouse and human PSC culture protocols have complicated the translation of discoveries between these systems. We recently developed a novel chemical media formulation, expanded potential stem cell medium (EPSCM), that maintains mouse PSCs in a unique cellular state and extraembryonic differentiation capacity. Herein, we describe how EPSCM can be directly used to stably maintain human PSCs. We further demonstrate that human PSCs maintained in EPSCM can spontaneously form embryoid bodies and undergo in vitro hematopoiesis using a simple differentiation protocol, similar to mouse PSC differentiation. EPSCM-maintained human PSCs generated at least two hematopoietic cell populations, which displayed distinct transcriptional profiles by RNA-sequencing (RNA-seq) analysis. EPSCM also supports gene targeting using homologous recombination, affording generation of an SPI1 (PU.1) reporter PSC line to study and track in vitro hematopoiesis. EPSCM therefore provides a useful tool not only to study pluripotency but also hematopoietic cell specification and developmental-lineage commitment.

Transplantation of cardiac Sca-1-positive cells rather than c-Kit-positive cells preserves mitochondrial oxygen consumption of the viable myocardium following myocardial infarction in rats

The cardiosphere-derived cell (CDC) is one of the candidate cells used for cardiac regenerative therapy. Cardiospheres are mixture of cells including c-Kit+ cells, stem cell antigen (Sca)-1+ cells, and other types of cardiac progenitor cells. In this study, we compared the effect of transplantation of isolated Sca-1+ cells and c-Kit+ cells with that of the crude CDCs (CrCDCs). Focusing on the differences in the ability for secretion of paracrine factors among 3 types of cells, we determined the effects of transplantation of these cells on cardiac intracellular signaling and mitochondrial function in rats with permanently ligated coronary arteries. We showed that the transplantation of these cells resulted in a preservation of the cardiac pump function and mitochondrial respiration at the 8th week after myocardial infarction. However, mitochondrial function in the c-Kit+ cell-transplanted group was lower than that in the other 2 groups. Furthermore, we found that activation levels of intracellular signaling proteins after cell transplantation may have been due to the ability of secretion of growth factors by these transplanted cell types. Our findings indicate the possibility that CrCDC and Sca-1+ cells rather than c-Kit+ cells may be used therapeutically to preserve cardiac function and energy metabolism after myocardial infarction.

Treatment with mononuclear cell populations improves post-infarction cardiac function but does not reduce arrhythmia susceptibility.

BackgroundClinical and experimental data give evidence that transplantation of stem and progenitor cells in myocardial infarction could be beneficial, although the underlying mechanism has remained elusive. Ventricular tachyarrhythmia is the most frequent and potentially lethal complication of myocardial infarction, but the impact of mono nuclear cells on the incidence of ventricular arrhythmia is still not clear.ObjectiveWe aimed to characterize the influence of splenic mononuclear cell populations on ventricular arrhythmia after myocardial infarction.MethodsWe assessed electrical vulnerability in vivo in mice with left ventricular cryoinfarction 14 days after injury and intramyocardial injection of specific subpopulations of mononuclear cells (MNCs) (CD11b-positive cells, Sca-1-positive cells, early endothelial progenitor cells (eEPCs)). As positive control group we used embryonic cardiomyocytes (eCMs). Epicardial mapping was performed for analysing conduction velocities in the border zone. Left ventricular function was quantified by echocardiography and left heart catheterization.ResultsIn vivo pacing protocols induced ventricular tachycardia (VT) in 30% of non-infarcted mice. In contrast, monomorphic or polymorphic VT could be evoked in 94% of infarcted and vehicle-injected mice (p<0.01). Only transplantation of eCMs prevented post-infarction VT and improved conduction velocities in the border zone in accordance to increased expression of connexin 43. Cryoinfarction resulted in a broad aggravation of left ventricular function. All transplanted cell types augmented left ventricular function to a similar extent.ConclusionsTransplantation of different MNC populations after myocardial infarction improves left ventricular function similar to effects of eCMs. Prevention of inducible ventricular arrhythmia is only seen after transplantation of eCMs.

Bone marrow CD34+ cell subset under induction of moderate stiffness of extracellular matrix after myocardial infarction facilitated endothelial lineage commitment in vitro

BackgroundThe stiffness of the myocardial extracellular matrix (ECM) and the transplanted cell type are vitally important in promoting angiogenesis. However, the combined effect of the two factors remains uncertain. The purpose of this study is to investigate in vitro the combined effect of myocardial ECM stiffness postinfarction with a bone marrow-derived cell subset expressing or not expressing CD34 on endothelial lineage commitment.MethodsMyocardial stiffness of the infarct zone was determined in mice at 1 h, 24 h, 7 days, 14 days, and 28 days after coronary artery ligation. Polyacrylamide (PA) gel substrates of different stiffnesses were prepared to mechanically mimic the myocardial ECM after infarction. Mouse bone marrow-derived CD34+ and CD34– cells were seeded on the flexible PA gels. The double-positive expression for DiI-acetylated low-density lipoprotein (acLDL) uptake and fluorescein isothiocyanate-Ulex europaeus agglutinin-1 (FITC-UEA-1) binding, the endothelial lineage antigens CD31, von Willebrand factor (vWF), Flk-1, and VE-cadherin, as well as cytoskeleton were measured by immunofluorescent staining on day 7. Cell apoptosis was evaluated by both immunofluorescent staining and flow cytometry at 24 h after culture.ResultsWe found that the numbers of the CD34+ cell subset adherent to the flexible substrates (4–72 kPa) was much larger than that of the CD34– subset. More double-positive cells for DiI-acLDL uptake/FITC-UEA-1 binding were seen on the 42-kPa (moderately stiff) substrate, corresponding to the stiffness of myocardial ECM at 7–14 days postinfarction, compared with those on substrates of other stiffnesses. Similarly, the moderately stiff substrate showed benefits in promoting the positive expressions of the endothelial lineage markers CD31, vWF, Flk-1, and VE-cadherin. In addition, the cytoskeleton F-actin network within CD34+ cells was organized more significantly at the leading edge of the adherent cells on the moderately stiff (42 kPa) or stiff (72 kPa) substrates as compared with those on the soft (4 kPa and 15 kPa) substrates. Moreover, the moderately stiff or stiff substrates showed a lower percentage of cell apoptosis than the soft substrates.ConclusionsInfarcted myocardium-like ECM of moderate stiffness (42 kPa) more beneficially regulated the endothelial lineage commitment of a bone marrow-derived CD34+ subset. Thus, the combination of a CD34+ subset with a “suitable” ECM stiffness might be an optimized strategy for cell-based cardiac repair.

Current Understanding of Stem Cell and Secretome Therapies in Liver Diseases.

Liver failure is one of the main risks of death worldwide, and it originates from repetitive injuries and inflammations of liver tissues, which finally leads to the liver cirrhosis or cancer. Currently, liver transplantation is the only effective treatment for the liver diseases although it has a limitation due to donor scarcity. Alternatively, cell therapy to regenerate and reconstruct the damaged liver has been suggested to overcome the current limitation of liver disease cures. Several transplantable cell types could be utilized for recovering liver functions in injured liver, including bone marrow cells, mesenchymal stem cells, hematopoietic stem cells, macrophages, and stem cell-derived hepatocytes. Furthermore, paracrine effects of transplanted cells have been suggested as a new paradigm for liver disease cures, and this application would be a new strategy to cure liver failures. Therefore, here we reviewed the current status and challenges of therapy using stem cells for liver disease treatments.

Transplantation of iPS cell-derived neural progenitors overexpressing SDF-1α increases regeneration and functional recovery after ischemic stroke.

Ischemic stroke is a leading cause of human death and disability while clinical treatments are limited. The adult brain possesses endogenous regenerative activities that may benefit tissue repair after stroke. Trophic factors such as stromal cell-derived factor 1 alpha (SDF-1α) are upregulated in the ischemic brain, which promote endogenous regeneration. The regenerative response, however, is normally insufficient. Transplantation of exogenous cells has been explored as regenerative therapies. One promising cell type for transplantation is induced pluripotent stem (iPS) cells which are cells genetically reprogrammed from adult somatic cells. We hypothesized that transplanting neural progenitor cells derived from iPS cells (iPS-NPCs) could provide cell replacement and trophic support. The trophic factor SDF-1α was overexpressed in iPS-NPCs by lentiviral transduction to test if SDF-1α could increase regeneration in the ischemic brain. These SDF-1α-iPS-NPCs were differentiated in vitro to express mature neuronal and synaptic markers. Differentiated cells expressed functional Na+ and K+ channels, and fired action potentials. In the oxygen glucose deprivation (OGD) test, SDF-1α-iPS-NPCs survived significantly better compared to control iPS-NPCs. In mice subjected to focal cerebral ischemia in the sensorimotor cortex, iPS-NPCs and SDF-1α-iPS-NPCs were intracranially transplanted into the ischemic cortex 7 days after stroke. Neuronal differentiation of transplanted cells was identified using NeuN 14 days after transplantation. Mice that received SDF-1α-iPS-NPCs had greater numbers of NeuN/BrdU and Glut-1/BrdU co-labeled cells in the peri-infarct area and improved locomotion compared to the control iPS-NPC transplantation. Thus, SDF-1α upregulation in transplanted cells may be a therapeutic strategy to enhance endogenous neurovascular repair after ischemic stroke in adult mice.

Pharmacological Reprogramming of Somatic Cells for Regenerative Medicine.

Lost or damaged cells in tissues and organs can be replaced by transplanting therapeutically competent cells. This approach requires methods that effectively manipulate cellular identities and properties to generate sufficient numbers of desired cell types for transplantation. These cells can be generated by reprogramming readily available somatic cells, such as fibroblasts, into induced pluripotent stem cells (iPSCs), which can replicate indefinitely and give rise to any somatic cell type. This reprogramming can be achieved with genetic methods, such as forced expression of pluripotency-inducing transcription factors (TFs), which can be further improved, or even avoided, with pharmacological agents. We screened chemical libraries for such agents and identified small molecules that enhance TF-mediated pluripotency induction in somatic cells. We also developed cocktails of small molecules that can functionally replace combinations of TFs required to induce pluripotency in mouse and human somatic cells. Importantly, we devised and established a general strategy to develop effective pharmacological cocktails for specific cellular reprogramming processes. In the search for useful small molecules, we also discovered and characterized previously unknown mechanisms pertinent to cellular reprogramming. A more direct method to access scarce cells for cell transplantation is transdifferentiation, which uses combinations of cell-type specific TFs to reprogram fibroblasts into the target somatic cell types across lineage boundaries. We created an alternative strategy for cellular transdifferentiation that epigenetically activates somatic cells by pairing temporal treatment with reprogramming molecules and tissue-specific signaling molecules to generate cells of multiple lineages. Using this cell-activation and signaling-directed (CASD) transdifferentiation paradigm, we converted fibroblasts into a variety of somatic cells found in major organs, such as the heart, brain, pancreas, and liver. Specifically, we induced, isolated, and expanded (long-term) lineage-specific progenitor cells that can give rise to a defined range of cell types relevant to specific tissues or organs. Transplanting these progenitor cells or their progeny was therapeutically beneficial in animal models of diseases and organ damage. Importantly, we developed chemically defined conditions, without any genetic factors, that convert fibroblasts into cells of the cardiac and neural lineages, further extending the realm of pharmacological reprogramming of cells. Continuously advancing technologies in pharmacological reprogramming of cells may benefit and advance regenerative medicine. The established pharmacological tools have already been applied to enhance the processes of cellular reprogramming and improve the quality of cells for their clinical applications. The rapidly increasing number of readily available bioactive chemical tools will fuel our efforts to reprogram cells for transplantation therapies.

Hematopoietic Stem Cells Therapies.

Stem cell-based therapies are recognized as a new way to treat various diseases and injuries, with a wide range of health benefits. The goal is to heal or replace diseased or destroyed organs or body parts with healthy new cells provided by stem cell transplantation. The current practical form of stem cell therapy is the hematopoietic stem cells transplant applied for the treatment of hematological disorders. There are over 2100 clinical studies in progress concerning hematopoietic stem cell therapies. All of them are using hematopoietic stem cells to treat various diseases like: cancers, leukemia, lymphoma, cardiac failure, neural disorders, auto-immune diseases, immunodeficiency, metabolic or genetic disorders. Several challenges are to be addressed prior to developing and applying large scale cell therapies: 1) to explain and control the mechanisms of differentiation and development toward a specific cell type needed to treat the disease, 2) to obtain a sufficient number of desired cell type for transplantation, 3) to overcome the immune rejection and 4) to show that transplanted cells fulfill their normal functions in vivo after transplants.

Gene correction in patient-specific iPSCs for therapy development and disease modeling.

The discovery that mature cells can be reprogrammed to become pluripotent and the development of engineered endonucleases for enhancing genome editing are two of the most exciting and impactful technology advances in modern medicine and science. Human pluripotent stem cells have the potential to establish new model systems for studying human developmental biology and disease mechanisms. Gene correction in patient-specific iPSCs can also provide a novel source for autologous cell therapy. Although historically challenging, precise genome editing in human iPSCs is becoming more feasible with the development of new genome-editing tools, including ZFNs, TALENs, and CRISPR. iPSCs derived from patients of a variety of diseases have been edited to correct disease-associated mutations and to generate isogenic cell lines. After directed differentiation, many of the corrected iPSCs showed restored functionality and demonstrated their potential in cell replacement therapy. Genome-wide analyses of gene-corrected iPSCs have collectively demonstrated a high fidelity of the engineered endonucleases. Remaining challenges in clinical translation of these technologies include maintaining genome integrity of the iPSC clones and the differentiated cells. Given the rapid advances in genome-editing technologies, gene correction is no longer the bottleneck in developing iPSC-based gene and cell therapies; generating functional and transplantable cell types from iPSCs remains the biggest challenge needing to be addressed by the research field.

Comparative Efficacies of Long-Term Serial Transplantation of Syngeneic, Allogeneic, Xenogeneic, or CTLA4Ig-Overproducing Xenogeneic Adipose Tissue-Derived Mesenchymal Stem Cells on Murine Systemic Lupus Erythematosus

Allogeneic and xenogeneic transplantation are suitable alternatives for treating patients with stem cell defects and autoimmune diseases. The purpose of this study was to compare the effects of long-term serial transplantation of adipose tissue-derived mesenchymal stem cells (ASCs) from (NZB × NZW) F1 mice (syngeneic), BALB/c mice (allogeneic), or humans (xenogeneic) on systemic lupus erythematosus (SLE). The effects of transplanting human ASCs overproducing CTLA4Ig (CTLA4Ig-hASC) were also compared. Animals were divided into five experimental groups, according to the transplanted cell type. Approximately 500,000 ASCs were administered intravenously every 2 weeks from 6 to 60 weeks of age to all mice except for the control mice, which received saline. The human ASC groups (hASC and CTLA4Ig-hASC) showed a 13-week increase in average life spans and increased survival rates and decreased blood urea nitrogen, proteinuria, and glomerular IgG deposition. The allogeneic group also showed higher survival rates compared to those of the control, up to 40, 41, 42, 43, 44, 45, 52, and 53 weeks of age. Syngeneic ASC transplantation did not accelerate the mortality of the mice. The mean life span of both the syngeneic and allogeneic groups was prolonged for 6-7 weeks. Both human ASC groups displayed increased serum interleukin-10 and interleukin-4 levels, whereas both mouse ASC groups displayed significantly increased GM-CSF and interferon-γ levels in the serum. The strongest humoral immune response was induced by xenogeneic transplantation, followed by allogeneic, CTLA4Ig-xenogeneic, and syngeneic transplantations. Long-term serial transplantation of the ASCs from various sources displayed different patterns of cytokine expression and humoral responses, but all of them increased life spans in an SLE mouse model.

Cell type–dependent variation in paracrine potency determines therapeutic efficacy against neonatal hyperoxic lung injury

Background aimsThe aim of this study was to determine the optimal cell type for transplantation to protect against neonatal hyperoxic lung injury. To this end, the in vitro and in vivo therapeutic efficacies and paracrine potencies of human umbilical cord blood–derived mesenchymal stromal cells (HUMs), human adipose tissue–derived mesenchymal stromal cells (HAMs) and human umbilical cord blood mononuclear cells (HMNs) were compared. MethodsHyperoxic injury was induced in vitro in A549 cells by challenge with H2O2. Alternatively, hyperoxic injury was induced in newborn Sprague-Dawley rats in vivo by exposure to hyperoxia (90% oxygen) for 14 days. HUMs, HAMs or HMNs (5 × 105 cells) were given intratracheally at postnatal day 5. ResultsHyperoxia-induced increases in in vitro cell death and in vivo impaired alveolarization were significantly attenuated in both the HUM and HAM groups but not in the HMN group. Hyperoxia impaired angiogenesis, increased the cell death and pulmonary macrophages and elevated inflammatory cytokine levels. These effects were significantly decreased in the HUM group but not in the HAM or HMN groups. The levels of human vascular endothelial growth factor and hepatocyte growth factor produced by donor cells were highest in HUM group, followed by HAM group and then HMN group. ConclusionsHUMs exhibited the best therapeutic efficacy and paracrine potency than HAMs or HMNs in protecting against neonatal hyperoxic lung injury. These cell type-dependent variations in therapeutic efficacy might be associated or mediated with the paracrine potency of the transplanted donor cells.

Genomic Editing of Stem Cells for Modeling and Therapy of Genetic Diseases

The application of advanced genome editing technologies, when combined with induced pluripotent stem cells (iPSC), presents a unique opportunity to develop unprecedented patient‐specific in vitro models of disease‐in‐a‐dish that can be used for the development of more effective and universal stem cell therapies. Towards this aim, we have corrected SCID‐X1 patient‐derived iPSC using TALENs, resulting in the rescue of defective IL2RG expression and in the recovered generation of lymphoid cells derived from these iPSC. We have also corrected the common ΔF508 mutation of CFTR in cystic fibrosis patient‐derived iPSC using a novel, efficient, footprint‐free CRISPR‐mediated approach, and shown the subsequent functional recovery of CFTR function in airway epithelium derived from the corrected iPSC.However, the inability to derive truly transplantable cell types from iPSC limits the long‐term clinical and therapeutic potential of this approach. To address this we have carried out direct CRISPR‐mediated gene correction of CD34+ hematopoietic stem cells (HSC) from the FoxP3 mutant scurfy (sf) NOD mouse, which is defective for the development of regulatory T‐cells. These directly gene‐edited FoxP3sf HSC can then be evaluated for their potential for long‐term engraftment and regeneration of regulatory T‐cells by transplantation into lethally irradiated recipient mice. The ultimate goal is to establish novel pre‐clinical models for stem cell‐based therapy for a variety of genetic disorders.

Efficacy of intervertebral disc regeneration with stem cells — A systematic review and meta-analysis of animal controlled trials

Management of intervertebral disc (IVD) degenerative disease is challenging, as it is accompanied by irreversible loss of IVD cells. Stem cell transplantation to the disc has shown promise in decelerating or arresting the degenerative process. Multiple pre-clinical animal trials have been conducted, but with conflicting outcomes. To assess the effect of stem cell transplantation, a systematic review and meta-analysis was performed. A comprehensive literature search was conducted through Week 3, 2015. Inclusion criteria consisted of controlled animal trials. Two reviewers screened abstracts and full texts. Disagreements were resolved by a third reviewer. Random effects models were constructed to pool standardized mean difference (SMD). Twenty two studies were included; nine of which were randomized. Statistically significant differences were found with the stem cell group exhibiting increased disc height index (SMD=3.64, 95% confidence interval (CI): 2.49, 4.78; p<0.001), increased MRI T2 signal intensity (SMD=2.28, 95% CI: 1.48, 3.08; p<0.001), increased Type II collagen mRNA expression (SMD=3.68, 95% CI: 1.66, 5.70; p<0.001), and decreased histologic disc degeneration grade (SMD=−2.97, 95% CI: −3.97, −1.97; p<0.001). There was statistical heterogeneity between studies that could not be explained with pre-planned subgroup analyses based on animal species, study designs, and transplanted cell types. Stem cells transplanted to the IVD in quadruped animals decelerate or arrest the IVD degenerative process. Further studies in human clinical trials will be needed to understand if such benefit can be translated to bipedal humans.

Thermoswitching microgel carriers improve neuronal cell growth and cell release for cell transplantation.

Successful cell replacement therapy in the central nervous system (CNS) depends on both the transplanted cell type and the cell delivery method. It was established that differentiated neurons are the most desirable cell source; however, they are highly sensitive to dissociation shear; removing them from the growth surface inflicts serious damage, rendering them less viable for transplantation. Pilot experiments using glass colloids as injectable cell carriers for cell transplantation in the adult rat hippocampus have greatly improved neuron survival and long-term neuron integration. However, these early studies have highlighted glass particle shortcomings. They are uncompressible, and, thus, only a small number of beads can be injected, limiting the transplanted cell number. Moreover, they remain permanently in the brain. To improve colloidal carriers properties for cell transplantation and establish a basis for the next generation of cell delivery supports, we have designed a broadly applicable engineering strategy to enable neuronal cell growth on and release from hydrogel particles before transplantation. Here, we describe poly(N-isopropylacrylamide) (pNIPAM) particle preparation, and we demonstrate that these hydrogel particles both facilitate manipulation of neurons and enable the increase in the number of viable transplanted cells in the young adult rat hippocampus. The absence of long-term cell association to beads suggested that pNIPAM thermoswitching properties enable the separation of cells from the beads during injection, which minimizes the number of injected carriers. Contrary to observations with glass carriers, no particle clumping was observed at the injection site, which indicates minimal risk of long-term inflammatory responses. Taken together, the properties of hydrogel particles make them a promising micro-carrier to improve neuronal cell transplantation.

Generation of Human Induced Pluripotent Stem Cells Using RNA-Based Sendai Virus System and Pluripotency Validation of the Resulting Cell Population.

Human induced pluripotent stem cells (hiPSCs) provide a platform for studying human disease in vitro, increase our understanding of human embryonic development, and provide clinically relevant cell types for transplantation, drug testing, and toxicology studies. Since their discovery, numerous advances have been made in order to eliminate issues such as vector integration into the host genome, low reprogramming efficiency, incomplete reprogramming and acquisition of genomic instabilities. One of the ways to achieve integration-free reprogramming is by using RNA-based Sendai virus. Here we describe a method to generate hiPSCs with Sendai virus in both feeder-free and feeder-dependent culture systems. Additionally, we illustrate methods by which to validate pluripotency of the resulting stem cell population.

The vascular stem cell niche: roadmap for transplanted neural progenitor cells during environmental enrichment?

One of the challenges of cell transplantation into the brain is poor graft survival. Graft survival may be affected by an immunological response of the host towards transplanted cells, shear injury to cells during transplantation or an unsuitable micro-environment for the transplanted cell type. Neural progenitor cells have an affinity to laminin, which is commonly used to maintain neural progenitors as monolayer cultures in vitro. The affinity of neural progenitor cells to laminin is based on the high expression of α6β1 integrin, which is required for binding of neural progenitors to endothelial cells (Hall et al., 2006; Shen et al., 2008). Mice with targeted disruption of β1 integrin have substantial layering deficits in developing neocortex (Loulier et al., 2009). Laminin is an important constituent of the basal membrane of brain capillaries. We also found abundant expression of laminin in the basal cistern along the apical surface of the molecular layer of the dentate gyrus (Jamal et al., 2015). Transplanted dentate progenitor cells did not survive in the transplant core within the dentate gyrus, but initially rather exclusively survived along the laminin scaffold of the basal cistern (Figure 1A). The laminin of the basal cistern is connected to the laminin of the capillary network of the dentate gyrus. It appeared as if transplanted dentate progenitor cells initially settled on the dense laminin scaffold of the basal cistern and then migrated into the hippocampal formation using laminin of dentate capillaries as tram tracks (Figure ​Figure1B1B, ​,C).C). Even though we expanded neural progenitor cells on laminin-coated tissue culture flasks, which may have selected for neural progenitor cells with a strong affinity to laminin, we observed the same in vivo affinity to laminin after growing neural progenitor cells as neurospheres for 5 days before transplantation. Also, previous experiments with neural progenitor cells grown exclusively as neurospheres before transplantation showed the greatest survival of cells along the laminin-rich basal cistern adjacent to the dentate gyrus instead of in the transplant core within the parenchyma of the hippocampal formation (Waldau et al., 2010).

Long-term survival, axonal growth-promotion, and myelination of Schwann cells grafted into contused spinal cord in adult rats

Schwann cells (SCs) have been considered to be one of the most promising cell types for transplantation to treat spinal cord injury (SCI) due to their unique growth-promoting properties. Despite the extensive use as donor cells for transplantation in SCI models, the fate of SCs is controversial due in part to the lack of a reliable marker for tracing the grafted SCs. To precisely assess the fate and temporal profile of transplanted SCs, we isolated purified SCs from sciatic nerves of adult transgenic rats overexpressing GFP (SCs-GFP). SCs-GFP were directly injected into the epicenter of a moderate contusive SCI at the mid-thoracic level at 1week post-injury. The number of SCs-GFP or SCs-GFP labeled with Bromodeoxyuridine (BrdU) was quantified at 5min, 1day, and 1, 2, 4, 12 and 24weeks after cell injection. Basso, Beattie, and Bresnahan (BBB) locomotor rating scale, footfall error, thermal withdrawal latency, and footprint analysis were performed before and after the SCs-GFP transplantation. After transplantation, SCs-GFP quickly filled the lesion cavity. A remarkable survival of grafted SCs-GFP up to 24weeks post-grafting was observed with clearly identified SC individuals. SCs-GFP proliferated after injection, peaked at 2weeks (26% of total SCs-GFP), decreased thereafter, and ceased at 12weeks post-grafting. Although grafted SCs-GFP were mainly confined within the border of surrounding host tissue, they migrated along the central canal for up to 5.0mm at 4weeks post-grafting. Within the lesion site, grafted SCs-GFP myelinated regenerated axons and expressed protein zero (P0) and myelin basic protein (MBP). Within the SCs-GFP grafts, new blood vessels were formed. Except for a significant decrease of angle of rotation in the footprint analysis, we did not observe significant behavioral improvements in BBB locomotor rating scale, thermal withdrawal latency, or footfall errors, compared to the control animals that received no SCs-GFP. We conclude that SCs-GFP can survive remarkably well, proliferate, migrate along the central canal, and myelinate regenerated axons when being grafted into a clinically-relevant contusive SCI in adult rats. Combinatorial strategies, however, are essential to achieve a more meaningful functional regeneration of which SCs may play a significant role.