From "Bench to Bedside": Current Advancement on Large-Scale Production of Mesenchymal Stem Cells

Microbead Encapsulation Strategy for Efficient Production of Extracellular Vesicles Derived From Human Mesenchymal Stem Cells

Human mesenchymal stem cell-derived extracellular vesicles (hMSC-EVs) have shown great potential in tissue repair and regeneration. However, their scalable production and functional quality are still limited by current expansion technologies. In this study, we propose a production technology for hMSC-EVs based on three-dimensional (3D) microbead culture, which enhances the secretory behaviour of hMSC. Fixed number of MSCs were encapsulated in Matrigel at appropriate densities and printed into 3D microbeads by the custom automated microfluidic bead-jet printing technique. Compared with 2D culture group, EVs derived from 3D hMSC microbead had smaller size and increased yield by 20-fold, and the actin depolymerisation of the cell may be an important mechanism for enhancing EV secretion. Further analysis confirmed that the EVs derived from 3D hMSC microbead exhibited enhanced angiogenic and proliferative capabilities, which promoted the viability and tube-forming capacity of human umbilical vein endothelial cells (HUVEC). In conclusion, this automated microfluidic microbead encapsulation technology increased the yield and therapeutic effect of hMSC-EVs and provides a platform for scalable EV production of regenerative therapies.

Mesangiogenic progenitor cells: a mesengenic and vasculogenic branch of hemopoiesis? A story of neglected plasticity

Mesangiogenic progenitor cells (MPCs) are mesengenic and vasculogenic cells isolated from human bone marrow mononuclear cell cultures. Although MPCs were first described over two decades ago and have demonstrated promising differentiation capabilities, these cells did not attract sufficient attention from experts in the field of tissue regeneration. Several reports from the first decade of the 2000s showed MPC-like cells co-isolated in primary mesenchymal stromal cell (MSC) cultures, applying human serum. However, in most cases, these rounded and firmly attached cells were described as "contaminating" cells of hemopoietic origin. Indeed, MPC morphology, phenotype, and functional features evoke but do not completely overlap with those of cultured peripheral macrophages, and their hemopoietic origin should not be excluded. The plasticity of cells from the monocyte lineage is surprising but not completely unprecedented. Underestimated data demonstrated that circulating monocyte/macrophages could acquire broader plasticity under specific and different culture conditions, and this plasticity could be a consequence of in vitro de-differentiation. The evidence discussed here suggests that MPCs could represent the cell identity toward which the de-differentiation process reprograms the circulating mature phagocytic compartment.

Improved Preservation of Rat Small Intestine Transplantation Graft by Introduction of Mesenchymal Stem Cell-Secreted Fractions

Segmental grafts from living donors have advantages over grafts from deceased donors when used for small intestine transplantation. However, storage time for small intestine grafts can be extremely short and optimal graft preservation conditions for short-term storage remain undetermined. Secreted factors from mesenchymal stem cells (MSCs) that allow direct activation of preserved small intestine grafts. Freshly excised Luc-Tg LEW rat tissues were incubated in preservation solutions containing MSC-conditioned medium (MSC-CM). Preserved Luc-Tg rat-derived grafts were then transplanted to wild-type recipients, after which survival, injury score, and tight junction protein expression were examined. Luminance for each graft was determined using in vivo imaging. The findings indicated that 30-100 and 3-10 kDa fractions of MSC-CM have superior activating effects for small intestine preservation. Expression of the tight-junction proteins claudin-3, and zonula occludens-1 preserved for 24 h in University of Wisconsin (UW) solution containing MSC-CM with 50-100 kDa, as shown by immunostaining, also indicated effectiveness. Reflecting the improved graft preservation, MSC-CM preloading of grafts increased survival rate from 0% to 87%. This is the first report of successful transplantation of small intestine grafts preserved for more than 24 h using a rodent model to evaluate graft preservation conditions that mimic clinical conditions.

Fabrication of polymeric microspheres for biomedical applications

Polymeric microspheres (PMs) have attracted great attention in the field of biomedicine in the last several decades due to their small particle size, special functionalities shown on the surface and high surface-to-volume ratio. However, how to fabricate PMs which can meet the clinical needs and transform laboratory achievements to industrial scale-up still remains a challenge. Therefore, advanced fabrication technologies are pursued. In this review, we summarize the technologies used to fabricate PMs, including emulsion-based methods, microfluidics, spray drying, coacervation, supercritical fluid and superhydrophobic surface-mediated method and their advantages and disadvantages. We also review the different structures, properties and functions of the PMs and their applications in the fields of drug delivery, cell encapsulation and expansion, scaffolds in tissue engineering, transcatheter arterial embolization and artificial cells. Moreover, we discuss existing challenges and future perspectives for advancing fabrication technologies and biomedical applications of PMs.

A controllable gelatin-based microcarriers fabrication system for the whole procedures of MSCs amplification and tissue engineering

Biopolymer microbeads present substantial benefits for cell expansion, tissue engineering, and drug release applications. However, a fabrication system capable of producing homogeneous microspheres with high precision and controllability for cell proliferation, passaging, harvesting and downstream application is limited. Therefore, we developed a co-flow microfluidics-based system for the generation of uniform and size-controllable gelatin-based microcarriers (GMs) for mesenchymal stromal cells (MSCs) expansion and tissue engineering. Our evaluation of GMs revealed superior homogeneity and efficiency of cellular attachment, expansion and harvest, and MSCs expanded on GMs exhibited high viability while retaining differentiation multipotency. Optimization of passaging and harvesting protocols was achieved through the addition of blank GMs and treatment with collagenase, respectively. Furthermore, we demonstrated that MSC-loaded GMs were printable and could serve as building blocks for tissue regeneration scaffolds. These results suggested that our platform held promise for the fabrication of uniform GMs with downstream application of MSC culture, expansion and tissue engineering.

Genomic instability in long-term culture of human adipose-derived mesenchymal stromal cells

Mesenchymal stromal/stem cells stem (MSC) have been widely studied due to their great potential for application in tissue engineering and regenerative and translational medicine. In MSC-based therapy for human diseases, cell proliferation is required to obtain a large and adequate number of cells to ensure therapeutic efficacy. During in vitro culture, cells are under an artificial environment and manipulative stress that can affect genetic stability. Several regulatory agencies have established guidelines to ensure greater safety in cell-based regenerative and translational medicine, but there is no specific definition about the maximum number of passages that ensure the lowest possible risk in MSC-based regenerative medicine. In this context, the aim of this study was to analyze DNA damage and chromosome alterations in adipose-derived mesenchymal stromal cells (ADMSC) until the eleventh passage and to provide additional subsidies to regulatory agencies related to number of passages in these cells. Thus, two methods in genetic toxicology were adopted: comet assay and micronucleus test. The comet assay results showed an increase in DNA damage from the fifth passage onwards. The micronucleus test showed a statistically significant increase of micronucleus from the seventh passage onwards, indicating a possible mutagenic effect associated with the increase in the number of passages. Based on these results, it is important to emphasize the need to assess genetic toxicology and inclusion of new guidelines by regulatory agencies to guarantee the safety of MSC-based therapies for human diseases.

Nebulised mesenchymal stem cell derived extracellular vesicles ameliorate E. coli induced pneumonia in a rodent model

BACKGROUND

Mesenchymal stem cell (MSC) derived extracellular vesicles (EVs) have been proposed as an alternative to cell therapy, creating new possible delivery modalities such as nebulisation. We wished to investigate the therapeutic potential of directly nebulised MSC-EVs in the mitigation of Escherichia coli-induced pneumonia.

METHODS

EV size, surface markers and miRNA content were assessed pre- and post-nebulisation. BEAS2B and A459 lung cells were exposed to lipopolysaccharide (LPS) and treated with nebulised bone marrow (BM) or umbilical cord (UC) MSC-EVs. Viability assays (MTT) and inflammatory cytokine assays were performed. THP-1 monocytes were stimulated with LPS and nebulised BM- or UC-EVs and phagocytosis activity was measured. For in vivo experiments, mice received LPS intratracheally (IT) followed by BM- or UC-EVs intravenously (IV) and injury markers assessed at 24 h. Rats were instilled with E. coli bacteria IT and BM- or UC-EVs delivered IV or by direct nebulisation. At 48 h, lung damage was assessed by physiological parameters, histology and inflammatory marker presence.

RESULTS

MSC-EVs retained their immunomodulatory and wound healing capacity after nebulisation in vitro. EV integrity and content were also preserved. Therapy with IV or nebulised MSC-EVs reduced the severity of LPS-induced lung injury and E. coli-induced pneumonia by reducing bacterial load and oedema, increasing blood oxygenation and improving lung histological scores. MSC-EV treated animals also showed lower levels of inflammatory cytokines and inflammatory-related markers.

CONCLUSIONS

MSC-EVs given IV attenuated LPS-induced lung injury, and nebulisation of MSC-EVs did not affect their capacity to attenuate lung injury caused by E. coli pneumonia, as evidenced by reduction in bacterial load and improved lung physiology.

Nebulized mesenchymal stem cell derived conditioned medium ameliorates Escherichia coli induced pneumonia in a rat model

Background

Mesenchymal stem cells (MSC) have shown immense therapeutic promise in a range of inflammatory diseases, including acute respiratory distress syndrome (ARDS), and are rapidly advancing through clinical trials. Among their multimodal mechanisms of action, MSCs exert strong immunomodulatory effects via their secretome, which contains cytokines, small molecules, extracellular vesicles, and a range of other factors. Recent studies have shown that the MSC secretome can recapitulate many of the beneficial effects of the MSC itself. We aimed to determine the therapeutic capacity of the MSC secretome in a rat bacterial pneumonia model, especially when delivered directly to the lung by nebulization which is a technique more appropriate for the ventilated patient.

Methods

Conditioned medium (CM) was generated from human bone marrow derived MSCs in the absence of antibiotics and serum supplements. Post-nebulization lung penetration was estimated through nebulization of CM to a cascade impactor and simulated lung and quantification of collected total protein and IL-8 cytokine. Control and nebulized CM was added to a variety of lung cell culture models and injury resolution assessed. In a rat E. coli pneumonia model, CM was instilled or administered by nebulization and lung injury and inflammation assessed at 48 h.

Results

MSC-CM was predicted to have good distal lung penetration and delivery when administered by nebulizer. Both control and nebulized CM reduced NF-κB activation and inflammatory cytokine production in lung cell culture, while promoting cell viability and would closure in oxidative stress and scratch wound models. In a rat bacterial pneumonia model, both instilled and nebulizer delivered CM improved lung function, increasing blood oxygenation and reducing carbon dioxide levels compared to unconditioned medium controls. A reduction in bacterial load was also observed in both treatment groups. Inflammatory cytokines were reduced significantly by both liquid and aerosol CM administration, with less IL-1β, IL-6, and CINC1 in these groups compared to controls.

Conclusion

MSC-CM is a potential therapeutic for pneumonia ARDS, and administration is compatible with vibrating mesh nebulization.

A scalable culture system incorporating microcarrier for specialised mesenchymal stem cells from human embryonic stem cells

Mesenchymal stromal cells (MSCs) derived from human embryonic stem cells (hESCs) are a desirable cell source for cell therapy owing to their capacity to be produced stably and homogeneously in large quantities. However, a scalable culture system for hPSC-derived MSCs is urgently needed to meet the cell quantity and quality requirements of practical clinical applications. In this study, we developed a new microcarrier with hyaluronic acid (HA) as the core material, which allowed scalable serum-free suspension culture of hESC-derived MSCs (IMRCs). We used optimal microcarriers with a coating collagen concentration of 100 ​μg/mL or concave-structured surface (cHAMCs) for IMRC amplification in a stirred bioreactor, expanding IMRCs within six days with the highest yield of over one million cells per milliliter. In addition, the harvested cells exhibited high viability, immunomodulatory and regenerative therapeutic promise comparable to monolayer cultured MSCs while showing more increased secretion of extracellular matrix (ECM), particularly collagen-related proteins. In summary, we have established a scalable culture system for hESC-MSCs, providing novel approaches for future cell therapies.

Erectile Dysfunction Treatment Using Stem Cell Delivery Patch in a Cavernous Nerve Injury Rat Model

Erectile dysfunction (ED) is a common and feared complication of radical prostatectomy (RP) for prostate cancer. Recently, tissue engineering for post-prostatectomy ED has been attempted in which controlled interactions between cells, growth factors, and the extracellular matrix (ECM) are important for the structural integrity if nerve regeneration. In this study, we evaluated the effects of a biomechanical ECM patch on the morphology and behavior of human bone marrow-derived mesenchymal stem cells (hBMSCs) in a bilateral cavernous nerve injury (BCNI) rat model. The ECM patch, made of decellularized human fibroblast-derived ECM (hFDM) and a biocompatible polyvinyl alcohol (PVA) hydrogel, was tested with human bone marrow-derived mesenchymal stem cells (hBMSCs) on a bilateral cavernous nerve injury (BCNI) rat model. In vitro analysis showed that the hFDM/PVA + hBMSCs patches significantly increased neural development markers. In vivo experiments demonstrated that the rats treated with the hFDM/PVA patch had higher ICP/MAP ratios, higher ratios of smooth muscle to collagen, increased nNOS content, higher levels of eNOS protein expression, and higher cGMP levels compared to the BCNI group. These results indicate that the hFDM/PVA patch is effective in promoting angiogenesis, smooth muscle regeneration, and nitrergic nerve regeneration, which could contribute to improved erectile function in post-prostatectomy ED.

Human umbilical cord-derived mesenchymal stem cells-harvested mitochondrial transplantation improved motor function in TBI models through rescuing neuronal cells from apoptosis and alleviating astrogliosis and microglia activation

Each year, traumatic brain injury (TBI) causes a high rate of mortality throughout the world and those who survive have lasting disabilities. Given that the brain is a particularly dynamic organ with a high energy consumption rate, the inefficiency of current TBI treatment options highlights the necessity of repairing damaged brain tissue at the cellular and molecular levels, which according to research is aggravated due to ATP deficiency and reactive oxygen species surplus. Taking into account that mitochondria contribute to generating energy and controlling cellular stress, mitochondrial transplantation as a new treatment approach has lately reduced complications in a number of diseases by supplying healthy and functional mitochondria to the damaged tissue. For this reason, in this study, we used this technique to transplant human umbilical cord-derived mesenchymal stem cells (hUC-MSCs)-derived mitochondria as a suitable source for mitochondrial isolation into rat models of TBI to examine its therapeutic benefit and the results showed that the successful mitochondrial internalisation in the neuronal cells significantly reduced the number of brain cells undergoing apoptosis, alleviated astrogliosis and microglia activation, retained normal brain morphology and cytoarchitecture, and improved sensorimotor functions in a rat model of TBI. These data indicate that human umbilical cord-derived mesenchymal stem cells-isolated mitochondrial transplantation improves motor function in a rat model of TBI via rescuing neuronal cells from apoptosis and alleviating astrogliosis and microglia activation, maybe as a result of restoring the lost mitochondrial content.

Preclinical Research of Stem Cells: Challenges and Progress

In recent years, great breakthroughs have been made in basic research and clinical applications of stem cells in regenerative medicine and other fields, which continue to inspire people to explore the field of stem cells. With nearly unlimited self-renewal ability, stem cells can generate at least one type of highly differentiated daughter cell, which provides broad development prospects for the treatment of human organ damage and other diseases. In the field of stem cell research, related technologies for inducing or isolating stem cells are relatively mature, and a variety of stable stem cell lines have been successfully constructed. To realize the full clinical application of stem cells as soon as possible, it is more and more important to further optimize each stage of stem cell research while conforming to Current Good Manufacture Practices (cGMP) standards. Here, we synthesized recent developments in stem cell research and focus on the introduction of xenogenicity in the preclinical research process and the remaining problems of various cell bioreactors. Our goal is to promote the development of technologies for xeno-free culture and clinical expansion of stem cells through in-depth discussion of current research. This review will provide new insight into stem cell research protocols and will contribute to the creation of efficient and stable stem cell expansion systems.

Challenges and strategies: Scalable and efficient production of mesenchymal stem cells-derived exosomes for cell-free therapy

Exosomes are small membrane vesicles secreted by most cell types, and widely exist in cell supernatants and various body fluids. They can transmit numerous bioactive elements, such as proteins, nucleic acids, and lipids, to affect the gene expression and function of recipient cells. Mesenchymal stem cells (MSCs) have been confirmed to be a potentially promising therapy for tissue repair and regeneration. Accumulating studies demonstrated that the predominant regenerative paradigm of MSCs transplantation was the paracrine effect but not the differentiation effect. Exosomes secreted by MSCs also showed similar therapeutic effects as their parent cells and were considered to be used for cell-free regenerative medicine. However, the inefficient and limited production has hampered their development for clinical translation. In this review, we summarize potential methods to efficiently promote the yield of exosomes. We mainly focus on engineering the process of exosome biogenesis and secretion, altering the cell culture conditions, cell expansion through 3D dynamic culture and the isolation of exosomes. In addition, we also discuss the application of MSCs-derived exosomes as therapeutics in disease treatment.

Conditioned Medium of Mesenchymal Stromal Cells Loaded with Paclitaxel Is Effective in Preclinical Models of Triple-Negative Breast Cancer (TNBC)

Triple-negative breast cancer (TNBC) is a very aggressive disease even in its early stages and is characterized by a severe prognosis. Neoadjuvant chemotherapy is one of the milestones of treatment, and paclitaxel (PTX) is among the most active drugs used in this setting. However, despite its efficacy, peripheral neuropathy occurs in approximately 20-25% of cases and represents the dose-limiting toxicity of this drug. New deliverable strategies to ameliorate drug delivery and reduce side effects are keenly awaited to improve patients' outcomes. Mesenchymal stromal cells (MSCs) have recently been demonstrated as promising drug delivery vectors for cancer treatment. The aim of the present preclinical study is to explore the possibility of a cell therapy approach based on the use of MSCs loaded with PTX to treat TNBC-affected patients. For this purpose, we in vitro evaluated the viability, migration and colony formation of two TNBC cell lines, namely, MDA-MB-231 and BT549, treated with MSC-PTX conditioned medium (MSC-CM PTX) in comparison with both CM of MSCs not loaded with PTX (CTRL) and free PTX. We observed stronger inhibitory effects on survival, migration and tumorigenicity for MSC-CM PTX than for CTRL and free PTX in TNBC cell lines. Further studies will provide more information about activity and potentially open the possibility of using this new drug delivery vector in the context of a clinical study.

Roles of Cartilage-Resident Stem/Progenitor Cells in Cartilage Physiology, Development, Repair and Osteoarthritis

Osteoarthritis (OA) is a degenerative disease that causes irreversible destruction of articular cartilage for which there is no effective treatment at present. Although articular cartilage lacks intrinsic reparative capacity, numerous studies have confirmed the existence of cartilage-resident stem/progenitor cells (CSPCs) in the superficial zone (SFZ) of articular cartilage. CSPCs are characterized by the expression of mesenchymal stromal cell (MSC)-related surface markers, multilineage differentiation ability, colony formation ability, and migration ability in response to injury. In contrast to MSCs and chondrocytes, CSPCs exhibit extensive proliferative and chondrogenic potential with no signs of hypertrophic differentiation, highlighting them as suitable cell sources for cartilage repair. In this review, we focus on the organizational distribution, markers, cytological features and roles of CSPCs in cartilage development, homeostasis and repair, and the application potential of CSPCs in cartilage repair and OA therapies.

Platelet-Rich Plasma as an Alternative to Xenogeneic Sera in Cell-Based Therapies: A Need for Standardization

There has been an explosion in scientific interest in using human-platelet-rich plasma (PRP) as a substitute of xenogeneic sera in cell-based therapies. However, there is a need to create standardization in this field. This systematic review is based on literature searches in PubMed and Web of Science databases until June 2021. Forty-one studies completed the selection criteria. The composition of PRP was completely reported in less than 30% of the studies. PRP has been used as PRP-derived supernatant or non-activated PRP. Two ranges could be identified for platelet concentration, the first between 0.14 × 10⁶ and 0.80 × 10⁶ platelets/µL and the second between 1.086 × 10⁶ and 10 × 10⁶ platelets/µL. Several studies have pooled PRP with a pool size varying from four to nine donors. The optimal dose for the PRP or PRP supernatant is 10%. PRP or PRP-derived supernatants a have positive effect on MSC colony number and size, cell proliferation, cell differentiation and genetic stability. The use of leukocyte-depleted PRP has been demonstrated to be a feasible alternative to xenogeneic sera. However, there is a need to improve the description of the PRP preparation methodology as well as its composition. Several items are identified and reported to create guidelines for future research.

Pharmaceutical therapeutics for articular regeneration and restoration: state-of-the-art technology for screening small molecular drugs

Articular cartilage damage caused by sports injury or osteoarthritis (OA) has gained increased attention as a worldwide health burden. Pharmaceutical treatments are considered cost-effective means of promoting cartilage regeneration, but are limited by their inability to generate sufficient functional chondrocytes and modify disease progression. Small molecular chemical compounds are an abundant source of new pharmaceutical therapeutics for cartilage regeneration, as they have advantages in design, fabrication, and application, and, when used in combination, act as powerful tools for manipulating cellular fate. In this review, we present current achievements in the development of small molecular drugs for cartilage regeneration, particularly in the fields of chondrocyte generation and reversion of chondrocyte degenerative phenotypes. Several clinically or preclinically available small molecules, which have been shown to facilitate chondrogenesis, chondrocyte dedifferentiation, and cellular reprogramming, and subsequently ameliorate cartilage degeneration by targeting inflammation, matrix degradation, metabolism, and epigenetics, are summarized. Notably, this review introduces essential parameters for high-throughput screening strategies, including models of different chondrogenic cell sources, phenotype readout methodologies, and transferable advanced systems from other fields. Overall, this review provides new insights into future pharmaceutical therapies for cartilage regeneration.

In Vitro Strategies to Vascularize 3D Physiologically Relevant Models

Vascularization of 3D models represents a major challenge of tissue engineering and a key prerequisite for their clinical and industrial application. The use of prevascularized models built from dedicated materials could solve some of the actual limitations, such as suboptimal integration of the bioconstructs within the host tissue, and would provide more in vivo-like perfusable tissue and organ-specific platforms. In the last decade, the fabrication of vascularized physiologically relevant 3D constructs has been attempted by numerous tissue engineering strategies, which are classified here in microfluidic technology, 3D coculture models, namely, spheroids and organoids, and biofabrication. In this review, the recent advancements in prevascularization techniques and the increasing use of natural and synthetic materials to build physiological organ-specific models are discussed. Current drawbacks of each technology, future perspectives, and translation of vascularized tissue constructs toward clinics, pharmaceutical field, and industry are also presented. By combining complementary strategies, these models are envisioned to be successfully used for regenerative medicine and drug development in a near future.

Umbilical cord mesenchymal stem/stromal cells potential to treat organ disorders; an emerging strategy

Currently, mesenchymal stem/stromal cells (MSCs) have attracted growing attention in the context of cell-based therapy in regenerative medicine. Following the first successful procurement of human MSCs from bone marrow (BM), these cells isolation has been conducted from various origins, in particular, the umbilical cord (UC). Umbilical cord-derived mesenchymal stem/stromal cells (UC-MSCs) can be acquired by a non-invasive plan and simply cultured, and thereby signifies their superiority over MSCs derived from other sources for medical purposes. Due to their unique attributes, including self-renewal, multipotency, and accessibility concomitant with their immunosuppressive competence and lower ethical concerns, UC-MSCs therapy is described as encouraging therapeutic options in cell-based therapies. Regardless of their unique aptitude to adjust inflammatory response during tissue recovery and delivering solid milieu for tissue restoration, UC-MSCs can be differentiated into a diverse spectrum of adult cells (e.g., osteoblast, chondrocyte, type II alveolar, hepatocyte, and cardiomyocyte). Interestingly, they demonstrate a prolonged survival and longer telomeres compared with MSCs derived from other sources, suggesting that UC-MSCs are desired source to use in regenerative medicine. In the present review, we deliver a brief review of UC-MSCs isolation, expansion concomitantly with immunosuppressive activities, and try to collect and discuss recent pre-clinical and clinical researches based on the use of UC-MSCs in regenerative medicine, focusing on with special focus on in vivo researches.

Rejuvenation of Helicobacter pylori-Associated Atrophic Gastritis Through Concerted Actions of Placenta-Derived Mesenchymal Stem Cells Prevented Gastric Cancer

Chronic Helicobacter pylori infection causes gastric cancer via the progression of precancerous chronic atrophic gastritis (CAG). Therefore, repairing gastric atrophy could be a useful strategy in preventing H. pylori-associated gastric carcinogenesis. Although eradication of the bacterial pathogen offers one solution to this association, this study was designed to evaluate an alternative approach using mesenchymal stem cells to treat CAG and prevent carcinogenesis. Here, we used human placenta-derived mesenchymal stem cells (PD-MSCs) and their conditioned medium (CM) to treat H. pylori-associated CAG in a mice/cell model to explore their therapeutic effects and elucidate their molecular mechanisms. We compared the changes in the fecal microbiomes in response to PD-MSC treatments, and chronic H. pylori-infected mice were given ten treatments with PD-MSCs before being sacrificed for end point assays at around 36 weeks of age. These animals presented with significant reductions in the mean body weights of the control group, which were eradicated following PD-MSC treatment (p < 0.01). Significant changes in various pathological parameters including inflammation, gastric atrophy, erosions/ulcers, and dysplastic changes were noted in the control group (p < 0.01), but these were all significantly reduced in the PD-MSC/CM-treated groups. Lgr5+, Ki-67, H⁺/K⁺-ATPase, and Musashi-1 expressions were all significantly increased in the treated animals, while inflammatory mediators, MMP, and apoptotic executors were significantly decreased in the PD-MSC group compared to the control group (p < 0.001). Our model showed that H. pylori-initiated, high-salt diet-promoted gastric atrophic gastritis resulted in significant changes in the fecal microbiome at the phylum/genus level and that PD-MSC/CM interventions facilitated a return to more normal microbial communities. In conclusion, administration of PD-MSCs or their conditioned medium may present a novel rejuvenating agent in preventing the progression of H. pylori-associated premalignant lesions.

Structurally Dynamic Hydrogels for Biomedical Applications: Pursuing a Fine Balance between Macroscopic Stability and Microscopic Dynamics

Owing to their unique chemical and physical properties, hydrogels are attracting increasing attention in both basic and translational biomedical studies. Although the classical hydrogels with static networks have been widely reported for decades, a growing number of recent studies have shown that structurally dynamic hydrogels can better mimic the dynamics and functions of natural extracellular matrix (ECM) in soft tissues. These synthetic materials with defined compositions can recapitulate key chemical and biophysical properties of living tissues, providing an important means to understanding the mechanisms by which cells sense and remodel their surrounding microenvironments. This review begins with the overall expectation and design principles of dynamic hydrogels. We then highlight recent progress in the fabrication strategies of dynamic hydrogels including both degradation-dependent and degradation-independent approaches, followed by their unique properties and use in biomedical applications such as regenerative medicine, drug delivery, and 3D culture. Finally, challenges and emerging trends in the development and application of dynamic hydrogels are discussed.

The Isolation and Manufacture of GMP-Grade Bone Marrow Stromal Cells from Bone Specimens

Bone marrow stromal cells (BMSCs, also known as bone marrow mesenchymal stem cells) are a plastic-adherent heterogeneous cell population that contain inherent skeletal progenitors and a subset of multipotential skeletal stem cells (SSCs). Application of BMSCs in therapeutic protocols implies its isolation and expansion under good manufacturing practices (GMP). Here we describe the procedures we have found to successfully generate practical BMSCs numbers, with preserved biological potency.

Extracorporeal shock wave therapy combined with engineered mesenchymal stem cells expressing stromal cell-derived factor-1 can improve erectile dysfunction in streptozotocin-induced diabetic rats

Background

For erectile dysfunction (ED) in diabetes mellitus (DM) patients who have poor response to drugs, extracorporeal shock wave therapy (ESWT) and engineered mesenchymal stem cell (MSC) therapy have been studied as alternative treatment options. The objective of this study is to investigate whether ESWT in combination with stromal cell-derived factor-1 expressing engineered mesenchymal stem cell (SDF-1 eMSC) therapy can have synergistic effects on ED in streptozotocin-induced diabetic rats.

Methods

Fifty 8-week-old male Sprague-Dawley rats were randomly divided into five groups (N=10 per group): (I) Normal group, (II) DM ED, (III) DM ED + ESWT group, (IV) DM ED + SDF-1 eMSC group, and (V) DM ED + ESWT + SDF-1 eMSC group. Each groups were treated with bilateral injections of SDF-1 eMSC or ESWT following the experiment protocol for eight weeks.

Results

The ratio of ICP/MAP was distinctly higher in the DM ED + ESWT + SDF-1 eMSC group than that in the DM ED group. Concentration of α-smooth muscle actin (α-SMA) was elevated the highest in the DM ED + ESWT + SDF-1 eMSC group. Additionally, ESWT increased the intensity of SDF-1 expression in the corpus cavernosum. ESWT + SDF-1 eMSC treatment also induced neuronal nitric oxide synthase (nNOS) and NO/cGMP expression in the corpus cavernosum. Furthermore, numbers of penile progenitor cells were increased in DM ED rats.

Conclusions

Combined treatment of ESWT with SDF-1 eMSC treatment is more effective than by a single therapy. It could be used as a potential and effective synergistic treatment for DM ED.

Umbilical cord derived mesenchymal stromal cells in microcarrier based industrial scale culture sustain the immune regulatory functions

Mesenchymal stromal cells (MSCs) have been isolated from numerous sources and are potentially therapeutic against various diseases. Umbilical cord-derived MSCs (UC-MSCs) are considered superior to other tissue-derived MSCs since they have a higher proliferation rate and can be procured using less invasive surgical procedures. However, it has been recently reported that 2D culture systems, using conventional cell culture flasks, limit the mass production of MSCs for cell therapy. Therefore, the development of alternative technologies, including microcarrier-based cell culture in bioreactors, is required for the large-scale production and industrialization of MSC therapy. In this study, we aimed to optimize the culture conditions for UC-MSCs by using a good manufacturing practice (GMP)-compatible serum-free medium, developed in-house, and a small-scale (30 mL) bioreactor, which was later scaled up to 500 mL. UC-MSCs cultured in microcarrier-based bioreactors (MC-UC-MSCs) showed characteristics equivalent to those cultured statically in conventional cell culture flasks (ST-UC-MSCs), fulfilling the minimum International Society for Cellular Therapy criteria for MSCs. Additionally, we report, for the first time, the equivalent therapeutic effect of MC-UC-MSCs and ST-UC-MSCs in immunodeficient mice (graft-versus-host disease model). Lastly, we developed a semi-automated cell dispensing system, without bag-to-bag variation in the filled volume or cell concentration. In summary, our results show that the combination of our GMP-compatible serum-free and microcarrier-based culture systems is suitable for the mass production of MSCs at an industrial scale. Further improvements in this microcarrier-based cell culture system can contribute to lowering the cost of therapy and satisfying several unmet medical needs.

Identification of key genes in type 2 diabetes-induced erectile dysfunction rats with stem cell therapy through high-throughput sequencing and bioinformatic analysis

Diabetes mellitus erectile dysfunction (DMED) is a frequent complication of diabetes. Mesenchymal stem cell (MSC) therapy was demonstrated to improve erectile function in DMED. However, the pathogenesis of DMED and the mechanism by which MSCs function are still unclear. We established a rat model of DMED and gave MSC therapy through intracavernous injection. After transcriptome sequencing of rats' penile tissue, we identified a total of 1,097 overlapped differentially expressed genes (DEGs) of the normal control group, DMED group, and MSC-treated group, containing 189 upregulated genes and 908 downregulated genes. The enriched functions of upregulated DEGs included extracellular matrix organisation (GO:0030198), extracellular structure organisation (GO:0043062), and wound healing (GO:0042060), PPAR signalling pathway (rno03320), arachidonic acid metabolism (rno00590) and retinol metabolism (rno00830). The enriched functions of downregulated DEGs included peptidase activity (GO:0052547), hair follicle development (GO:0001942), intermediate filament-based process (GO:0045103), nitrogen metabolism (rno00910), aldosterone-regulated sodium reabsorption (rno04960) and retinol metabolism (rno00830). We constructed a PPI network with 547 nodes and 2,365 edges and identified 15 hub genes with high connectivity degree. In summary, 15 hub genes with potential roles in the development of ED were identified. Further functional research would be required to elucidate the molecular mechanism underlying misregulated genes.

Biomimetic Culture Strategies for the Clinical Expansion of Mesenchymal Stromal Cells

Mesenchymal stromal/stem cells (MSCs) typically require significant ex vivo expansion to achieve the high cell numbers required for research and clinical applications. However, conventional MSC culture on planar (2D) plastic surfaces has been shown to induce MSC senescence and decrease cell functionality over long-term proliferation, and usually, it has a high labor requirement, a high usage of reagents, and therefore, a high cost. In this Review, we describe current MSC-based therapeutic strategies and outline the important factors that need to be considered when developing next-generation cell expansion platforms. To retain the functional value of expanded MSCs, ex vivo culture systems should ideally recapitulate the components of the native stem cell microenvironment, which include soluble cues, resident cells, and the extracellular matrix substrate. We review the interplay between these stem cell niche components and their biological roles in governing MSC phenotype and functionality. We discuss current biomimetic strategies of incorporating biochemical and biophysical cues in MSC culture platforms to grow clinically relevant cell numbers while preserving cell potency and stemness. This Review summarizes the current state of MSC expansion technologies and the challenges that still need to be overcome for MSC clinical applications to be feasible and sustainable.

Mesenchymal stem cells modified by FGF21 and GLP1 ameliorate lipid metabolism while reducing blood glucose in type 2 diabetic mice

OBJECTIVE

The purpose of this study was to investigate the therapeutic effects of genetically modified mesenchymal stem cells (MSCs) in the treatment of type 2 diabetes mellitus (T2DM) in order to identify a new method for treating diabetes that differs from traditional medicine and to provide a new means by which to fundamentally improve or treat diabetes.

METHODS

MSCs derived from adipose tissue were modified to overexpress FGF21 and GLP1, which was achieved through lentiviral particle transduction. The cells were transplanted into BKS.Cg-Dock7m+/+Leprdb/Nju mice (T2DM mouse model). Injections of physiological saline (0.1 mL) and liraglutide (0.5 mg/kg) were used as negative and positive controls, respectively. ELISA or Western blotting was used for protein analysis, and quantitative real-time PCR was used for gene expression analysis.

RESULTS

Genetic modification had no effects on the morphology, differentiation ability, or immunophenotype of MSCs. Moreover, MSC-FGF21+GLP1 cells exhibited significantly increased secretion of FGF21 and GLP1. In the T2DM mouse model, the transplantation of MSC-FGF21+GLP1 cells ameliorated the changes in blood glucose and weight, promoted the secretion of insulin, enhanced the recovery of liver structures, and improved the profiles of lipids. Moreover, FGF21 and GLP1 exerted synergistic effects in the regulation of glucolipid metabolism by controlling the expression of insulin, srebp1, and srebp2.

CONCLUSION

Stem cell treatment based on MSCs modified to overexpress the FGF21 and GLP1 genes is an effective approach for the treatment of T2DM.

Mesenchymal stem cells as a multimodal treatment for nervous system diseases

Neurological disorders are a massive challenge for modern medicine. Apart from the fact that this group of diseases is the second leading cause of death worldwide, the majority of patients have no access to any possible effective and standardized treatment after being diagnosed, leaving them and their families helpless. This is the reason why such great emphasis is being placed on the development of new, more effective methods to treat neurological patients. Regenerative medicine opens new therapeutic approaches in neurology, including the use of cell-based therapies. In this review, we focus on summarizing one of the cell sources that can be applied as a multimodal treatment tool to overcome the complex issue of neurodegeneration-mesenchymal stem cells (MSCs). Apart from the highly proven safety of this approach, beneficial effects connected to this type of treatment have been observed. This review presents modes of action of MSCs, explained on the basis of data from vast in vitro and preclinical studies, and we summarize the effects of using these cells in clinical trial settings. Finally, we stress what improvements have already been made to clarify the exact mechanism of MSCs action, and we discuss potential ways to improve the introduction of MSC-based therapies in clinics. In summary, we propose that more insightful and methodical optimization, by combining careful preparation and administration, can enable use of multimodal MSCs as an effective, tailored cell therapy suited to specific neurological disorders.

Pressure Stimuli Improve the Proliferation of Wharton's Jelly-Derived Mesenchymal Stem Cells under Hypoxic Culture Conditions

Mesenchymal stem cells (MSCs) are safe, and they have good therapeutic efficacy through their paracrine action. However, long-term culture to produce sufficient MSCs for clinical use can result in side-effects, such as an inevitable senescence and the reduction of the therapeutic efficacy of the MSCs. In order to overcome this, the primary culture conditions of the MSCs can be modified to simulate the stem cells’ niche environment, resulting in accelerated proliferation, the achievement of the target production yield at earlier passages, and the improvement of the therapeutic efficacy. We exposed Wharton’s jelly-derived MSCs (WJ-MSCs) to pressure stimuli during the primary culture step. In order to evaluate the proliferation, stemness, and therapeutic efficacy of WJ-MSCs, image, genetic, and Western blot analyses were carried out. Compared with standard incubation culture conditions, the cell proliferation was significantly improved when the WJ-MSCs were exposed to pressure stimuli. However, the therapeutic efficacy (the promotion of cell proliferation and anti-apoptotic effects) and the stemness of the WJ-MSCs was maintained, regardless of the culture conditions. Exposure to pressure stimuli is a simple and efficient way to improve WJ-MSC proliferation without causing changes in stemness and therapeutic efficacy. In this way, clinical-grade WJ-MSCs can be produced rapidly and used for therapeutic applications.

Human hair follicle-derived mesenchymal stem cells: Isolation, expansion, and differentiation

Hair follicles are easily accessible skin appendages that protect against cold and potential injuries. Hair follicles contain various pools of stem cells, such as epithelial, melanocyte, and mesenchymal stem cells (MSCs) that continuously self-renew, differentiate, regulate hair growth, and maintain skin homeostasis. Recently, MSCs derived from the dermal papilla or dermal sheath of the human hair follicle have received attention because of their accessibility and broad differentiation potential. In this review, we describe the applications of human hair follicle-derived MSCs (hHF-MSCs) in tissue engineering and regenerative medicine. We have described protocols for isolating hHF-MSCs from human hair follicles and their culture condition in detail. We also summarize strategies for maintaining hHF-MSCs in a highly proliferative but undifferentiated state after repeated in vitro passages, including supplementation of growth factors, 3D suspension culture technology, and 3D aggregates of MSCs. In addition, we report the potential of hHF-MSCs in obtaining induced smooth muscle cells and tissue-engineered blood vessels, regenerated hair follicles, induced red blood cells, and induced pluripotent stem cells. In summary, the abundance, convenient accessibility, and broad differentiation potential make hHF-MSCs an ideal seed cell source of regenerative medical and cell therapy.

Limited Potential or Unfavorable Manipulations? Strategies Toward Efficient Mesenchymal Stem/Stromal Cell Applications

Despite almost 50 years of research and over 20 years of preclinical and clinical studies, the question of curative potential of mesenchymal stem/stromal cells (MSCs) is still widely discussed in the scientific community. Non-reproducible treatment outcomes or even absence of treatment effects in comparison to control groups challenges the potential of these cells for routine application both in tissue engineering and in regenerative medicine. One of the reasons of such outcomes is non-standardized and often disadvantageous ex vivo manipulation of MSCs prior therapy. In most cases, clinically relevant cell numbers for MSC-based therapies can be only obtained by in vitro expansion of isolated cells. In this mini review, we will discuss point by point possible pitfalls in the production of human MSCs for cell therapies, without consideration of material-based applications. Starting with cell source, choice of donor and recipient, as well as isolation methods, we will then discuss existing expansion protocols (two-/three-dimensional cultivation, basal medium, medium supplements, static/dynamic conditions, and hypoxic/normoxic conditions) and influence of these strategies on the cell functionality after implantation. The role of potency assays will also be addressed. The final aim of this mini review is to illustrate the heterogeneity of current strategies for gaining MSCs for clinical applications with their strengths and weaknesses. Only a careful consideration and standardization of all pretreatment processes/methods for the different applications of MSCs will ensure robust and reproducible performance of these cell populations in the different experimental and clinical settings.

Automated Large-Scale Production of Paclitaxel Loaded Mesenchymal Stromal Cells for Cell Therapy Applications

Mesenchymal stromal cells (MSCs) prepared as advanced therapies medicinal products (ATMPs) have been widely used for the treatment of different diseases. The latest developments concern the possibility to use MSCs as carrier of molecules, including chemotherapeutic drugs. Taking advantage of their intrinsic homing feature, MSCs may improve drugs localization in the disease area. However, for cell therapy applications, a significant number of MSCs loaded with the drug is required. We here investigate the possibility to produce a large amount of Good Manufacturing Practice (GMP)-compliant MSCs loaded with the chemotherapeutic drug Paclitaxel (MSCs-PTX), using a closed bioreactor system. Cells were obtained starting from 13 adipose tissue lipoaspirates. All samples were characterized in terms of number/viability, morphology, growth kinetics, and immunophenotype. The ability of MSCs to internalize PTX as well as the antiproliferative activity of the MSCs-PTX in vitro was also assessed. The results demonstrate that our approach allows a large scale expansion of cells within a week; the MSCs-PTX, despite a different morphology from MSCs, displayed the typical features of MSCs in terms of viability, adhesion capacity, and phenotype. In addition, MSCs showed the ability to internalize PTX and finally to kill cancer cells, inhibiting the proliferation of tumor lines in vitro. In summary our results demonstrate for the first time that it is possible to obtain, in a short time, large amounts of MSCs loaded with PTX to be used in clinical trials for the treatment of patients with oncological diseases.

"All-in-One" Gel System for Whole Procedure of Stem-Cell Amplification and Tissue Engineering

Microsphere (MS)-based systems provides great advantages for cell expansion and transplantation due to their high surface-to-volume ratio and biomimetic environment. However, a MS-based system that includes cell attachment, proliferation, passage, harvest, cryopreservation, and tissue engineering together has not been realized yet. An "all-in-one" gel MS-based system is established for human adipose-derived mesenchymal stem cells (hADSCs), realizing real 3D culture with enhanced expansion efficiency and simplified serial cell culture operations, and construction of macrotissues with uniform cell distribution and specific function. A 3D digital light-processing technology is developed to fabricate gel MSs in an effective way. The printed MSs present a suitable environment with rough surface architecture and the mechanical properties of soft tissues, leading to high cell viability, attachment, proliferation, activity, and differentiation potential. Further, convenient standard operation procedures, including cell passage, detachment, and cryopreservation, are established for cell culture on the gel MSs. Finally, hADSCs-loaded gel MSs form macrotissues through a "bottom-up" approach, which demonstrates the potential applications for tissue engineering. These findings exhibit the feasibility and beauty of "all-in-one" stem cell culture and tissue engineering system.

Unraveling the Molecular Signature of Extracellular Vesicles From Endometrial-Derived Mesenchymal Stem Cells: Potential Modulatory Effects and Therapeutic Applications

Endometrial-derived Mesenchymal Stem Cells (endMSCs) are involved in the regeneration and remodeling of human endometrium, being considered one of the most promising candidates for stem cell-based therapies. Their therapeutic effects have been found to be mediated by extracellular vesicles (EV-endMSCs) with pro-angiogenic, anti-apoptotic, and immunomodulatory effects. Based on that, the main goal of this study was to characterize the proteome and microRNAome of these EV-endMSCs by proteomics and transcriptomics approaches. Additionally, we hypothesized that inflammatory priming of endMSCs may contribute to modify the therapeutic potential of these vesicles. High-throughput proteomics revealed that 617 proteins were functionally annotated as Extracellular exosome (GO:0070062), corresponding to the 70% of the EV-endMSC proteome. Bioinformatics analyses allowed us to identify that these proteins were involved in adaptive/innate immune response, complement activation, antigen processing/presentation, negative regulation of apoptosis, and different signaling pathways, among others. Of note, multiplexed quantitative proteomics and Systems Biology analyses showed that IFNγ priming significantly modulated the protein profile of these vesicles. As expected, proteins involved in antigen processing and presentation were significantly increased. Interestingly, immunomodulatory proteins, such as CSF1, ERAP1, or PYCARD were modified. Regarding miRNAs expression profile in EV-endMSCs, Next-Generation Sequencing (NGS) showed that the preferred site of microRNAome targeting was the nucleus (n = 371 microTargets), significantly affecting signal transduction (GO:0007165), cell proliferation (GO:0008283), and apoptotic processes (GO:0006915), among others. Interestingly, NGS analyses highlighted that several miRNAs, such as hsa-miR-150-5p or hsa-miR-196b-5p, were differentially expressed in IFNγ-primed EV-endMSCs. These miRNAs have a functional involvement in glucocorticoid receptor signaling, IL-6/8/12 signaling, and in the role of macrophages. In summary, these results allowed us to understand the complexity of the molecular networks in EV-endMSCs and their potential effects on target cells. To our knowledge, this is the first comprehensive study based on proteomic and genomic approaches to unravel the therapeutic potential of these extracellular vesicles, that may be used as immunomodulatory effectors in the treatment of inflammatory conditions.

Efficacy and Safety of Umbilical Cord Mesenchymal Stem Cell Therapy for Rheumatoid Arthritis Patients: A Prospective Phase I/II Study

BACKGROUND

The traditional anti-inflammation disease-modifying anti-rheumatic drugs (DMARDs) have limited therapeutic effects in rheumatoid arthritis (RA) patients. We previously reported the safety and efficacy of umbilical cord mesenchymal stem cell (UC-MSC) treatment in RA patients that were observed for up to 8 months after UC-MSC infusion. The aim of this study is to assess the long-term efficacy and safety of UC-MSC along with DMARDs for the treatment of RA.

METHODS

64 RA patients aged 18-64 years were recruited in the study. During the treatment, patients were treated with 40 mL UC-MSC suspension product (2 × 107 cells/20 mL) via intravenous injection immediately after the infusion of 100 mL saline. The serological markers tests were used to assess safety and the 28-joint disease activity score (DAS28) and the Health Assessment Questionnaire (HAQ) to assess efficacy.

RESULTS

1 year and 3 years after UC-MSC cells treatment, the blood routine, liver and kidney function and immunoglobulin examination showed no abnormalities, which were all in the normal range. The ESR, CRP, RF of 1 year and 3 years after treatment and anti-CCP of 3 years after treatment were detected to be lower than that of pretreatment, which showed significant change (P < 0.05). Health index (HAQ) and joint function index (DAS28) decreased 1 year and 3 years after treatment than before treatment (P < 0.05).

CONCLUSION

UC-MSC cells plus DMARDs therapy can be a safe, effective and feasible therapeutic option for RA patients.

Large-Scale Automated Hollow-Fiber Bioreactor Expansion of Umbilical Cord-Derived Human Mesenchymal Stromal Cells for Neurological Disorders

Neurodegenerative disorders present a broad group of neurological diseases and remain one of the greatest challenges and burdens to mankind. Maladies like amyotrophic lateral sclerosis, Alzheimer's disease, stroke or spinal cord injury commonly features astroglia involvement (astrogliosis) with signs of inflammation. Regenerative, paracrine and immunomodulatory properties of human mesenchymal stromal cells (hMSCs) could target the above components, thus opening new therapeutic possibilities for regenerative medicine. A special interest should be given to hMSCs derived from the umbilical cord (UC) tissue, due to their origin, properties and lack of ethical paradigms. The aim of this study was to establish standard operating and scale-up good manufacturing practice (GMP) protocols of UC-hMSCs isolation, characterization, expansion and comparison of cells' properties when harvested on T-flasks versus using a large-scale bioreactor system. Human UC-hMSCs, isolated by tissue explant culture technique from Wharton's jelly, were harvested after reaching 75% confluence and cultured using tissue culture flasks. Obtained UC-hMSCs prior/after the cryopreservation and after harvesting in a bioreactor, were fully characterized for "mesenchymness" immunomodulatory, tumorigenicity and genetic stability, senescence and cell-doubling properties, as well as gene expression features. Our study demonstrates an efficient and simple technique for large scale UC-hMSCs expansion. Harvesting of UC-hMSCs' using classic and large scale methods did not alter UC-hMSCs' senescence, genetic stability or in vitro tumorigenicity features. We observed comparable growth and immunomodulatory capacities of fresh, frozen and expanded UC-hMSCs. We found no difference in the ability to differentiate toward adipogenic, osteogenic and chondrogenic lineages between classic and large scale UC-hMSCs expansion methods. Both, methods enabled derivation of genetically stabile cells with typical mesenchymal features. Interestingly, we found significantly increased mRNA expression levels of neural growth factor (NGF) and downregulated insulin growth factor (IGF) in UC-hMSCs cultured in bioreactor, while IL4, IL6, IL8, TGFb and VEGF expression levels remained at the similar levels. A culturing of UC-hMSCs using a large-scale automated closed bioreactor expansion system under the GMP conditions does not alter basic "mesenchymal" features and quality of the cells. Our study has been designed to pave a road toward translation of basic research data known about human UC-MSCs for the future clinical testing in patients with neurological and immunocompromised disorders. An industrial manufacturing of UC-hMSCs next will undergo regulatory approval following advanced therapy medicinal products (ATMP) criteria prior to clinical application and approval to be used in patients.

Principal Criteria for Evaluating the Quality, Safety and Efficacy of hMSC-Based Products in Clinical Practice: Current Approaches and Challenges

Human Mesenchymal Stem Cells (hMSCs) play an important role as new therapeutic alternatives in advanced therapies and regenerative medicine thanks to their regenerative and immunomodulatory properties, and ability to migrate to the exact area of injury. These properties have made hMSCs one of the more promising cellular active substances at present, particularly in terms of the development of new and innovative hMSC-based products. Currently, numerous clinical trials are being conducted to evaluate the therapeutic activity of hMSC-based products on specific targets. Given the rapidly growing number of hMSC clinical trials in recent years and the complexity of these products due to their cellular component characteristics and medicinal product status, there is a greater need to define more stringent, specific, and harmonized requirements to characterize the quality of the hMSCs and enhance the analysis of their safety and efficacy in final products to be administered to patients. These requirements should be implemented throughout the manufacturing process to guarantee the function and integrity of hMSCs and to ensure that the hMSC-based final product consistently meets its specifications across batches. This paper describes the principal phases involved in the design of the manufacturing process and updates the specific technical requirements needed to address the appropriate clinical use of hMSC-based products. The challenges and limitations to evaluating the safety, efficacy, and quality of hMSCs have been also reviewed and discussed.

Noninvasive application of mesenchymal stem cell spheres derived from hESC accelerates wound healing in a CXCL12-CXCR4 axis-dependent manner

Mesenchymal stem cells (MSC) derived from adult tissues effectively promote wound healing. However, MSC quality varies, and the quantity of MSC is limited, as MSC are acquired through donations. Moreover, the survival and functioning of dissociated MSC delivered to an inflammatory lesion are subject to challenges. Methods: Here, spheres (EMSCSp) generated from human embryonic stem cell-derived MSC (EMSC) were directly dropped onto excised wounds in mice; the effects of EMSCSp were compared to those of dissociated EMSC (EMSCDiss). Following transplantation, we measured the extent of wound closure, dissected the histological features of the wounds, determined transcriptomic changes in cells isolated from the treated and control wounds, and evaluated the molecular mechanism of the effects of EMSC. Results: The application of EMSCSp onto murine dermal wounds substantially increased survival and efficacy of EMSC compared to the topical application of EMSCDiss. RNA sequencing (RNA-Seq) of cells isolated from the wounds highlighted the involvement of CXCL12-CXCR4 signaling in the effects of EMSCSp, which was verified in EMSC via CXCL12 knockdown and in target cells (vascular endothelial cells, epithelial keratinocytes, and macrophages) via CXCR4 inhibition. Finally, we enhanced the biosafety of EMSCSp by engineering cells with an inducible suicide gene. Conclusions: Together, these data suggest the topical application of EMSCSp as an unlimited, quality-assured, safe, and noninvasive therapy for wound healing and the CXCL12-CXCR4 axis as a key player in this treatment.

Identification of senescent cells in multipotent mesenchymal stromal cell cultures: Current methods and future directions

Regardless of their tissue of origin, multipotent mesenchymal stromal cells (MSCs) are commonly expanded in vitro for several population doublings to achieve a sufficient number of cells for therapy. Prolonged MSC expansion has been shown to result in phenotypical, morphological and gene expression changes in MSCs, which ultimately lead to the state of senescence. The presence of senescent cells in therapeutic MSC batches is undesirable because it reduces their viability, differentiation potential and trophic capabilities. Additionally, senescent cells acquire senescence-activated secretory phenotype, which may not only induce apoptosis in the neighboring host cells following MSC transplantation, but also trigger local inflammatory reactions. This review outlines the current and promising new methodologies for the identification of senescent cells in MSC cultures, with a particular emphasis on non-destructive and label-free methodologies. Technologies allowing identification of individual senescent cells, based on new surface markers, offer potential advantage for targeted senescent cell removal using new-generation senolytic agents, and subsequent production of therapeutic MSC batches fully devoid of senescent cells. Methods or a combination of methods that are non-destructive and label-free, for example, involving cell size and spectroscopic measurements, could be the best way forward because they do not modify the cells of interest, thus maximizing the final output of therapeutic-grade MSC cultures. The further incorporation of machine learning methods has also recently shown promise in facilitating, automating and enhancing the analysis of these measured data.

Insulin-like growth factor 2 regulates the proliferation and differentiation of rat adipose-derived stromal cells via IGF-1R and IR

BACKGROUND

Insulin-like growth factor 2 (IGF2), an essential component of the stem cell niche, has been reported to modulate the proliferation and differentiation of stem cells. Previously, a continuous expression of IGF2 in tissues was reported to maintain the self-renewal ability of several types of stem cells. Therefore, in this study, we investigated the expression of IGF2 in adipose tissues and explored the effects of IGF2 on adipose-derived stromal cells (ADSCs) in vitro.

METHODS

The expression pattern of IGF2 in rat adipose tissues was determined by gene expression and protein analyses. The effect of IGF2 on proliferation, stemness-related marker expression and adipogenic and osteogenic differentiation was systematically investigated. Furthermore, antagonists of IGF2-specific receptors-namely, BMS-754807 and picropodophyllin-were added to explore the underlying signal transduction mechanisms.

RESULTS

IGF2 levels displayed a tendency to decrease with age in rat adipose tissues. After the addition of IGF2, isolated ADSCs displayed higher proliferation and expression of the stemness-related markers NANOG, OCT4 and SOX2 and greater differentiation potential to adipocytes and osteoblasts. Additionally, both type 1 insulin-like growth factor receptor (IGF-1R) and insulin receptor (IR) participated in the IGF2-mediated promotion of stemness in ADSCs.

CONCLUSIONS

Our findings indicate that IGF2 could enhance the stemness of rat ADSCs via IGF-1R and IR and may highlight an effective method for the expansion of ADSCs for clinical application.

Cartilage progenitor cells combined with PHBV in cartilage tissue engineering

Background

Bone marrow-derived stem cells (BMSCs) and chondrocytes have been reported to present “dedifferentiation” and “phenotypic loss” during the chondrogenic differentiation process in cartilage tissue engineering, and cartilage progenitor cells (CPCs) are novel seeding cells for cartilage tissue engineering. In our previous study, cartilage progenitor cells from different subtypes of cartilage tissue were isolated and identified in vitro, but the study on in vivo chondrogenic characteristics of cartilage progenitor cells remained rarely. In the current study, we explored the feasibility of combining cartilage progenitor cells with poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) to produce tissue-engineered cartilage and compared the proliferation ability and chondrogenic characteristics of cartilage progenitor cells with those of bone marrow-derived stem cells and chondrocytes.

Methods

These three cells combined with PHBV were cultured in vitro for 1 week without chondrogenic induction and then transplanted subcutaneously into nude mice for 6 weeks. The cell-PHBV constructs were evaluated by gross observation, histological staining, glycosaminoglycan content measurement, biomechanical analysis and RT-PCR.

Results

The chondrocyte-PHBV constructs and CPC-PHBV constructs became an ivory-whitish cartilage-like tissue, while the BMSC-PHBV constructs became vascularized 6 weeks after the subcutaneous implantation. Histological examination showed that many typical cartilage structures were present in the chondrocyte group, some typical cartilage structures were observed in the CPC group, while no typical cartilage structures were observed in the BMSC group.

Conclusions

Cartilage progenitor cells may undergo chondrogenesis without chondrogenic induction and are better at chondrogenesis than BMSCs but worse than chondrocytes in the application of cartilage tissue engineering.

Manufacturing of primed mesenchymal stromal cells for therapy

Mesenchymal stromal cells (MSCs) for basic research and clinical applications are manufactured and developed as unique cell products by many different manufacturers and laboratories, often under different conditions. The lack of standardization of MSC identity has limited consensus around which MSC properties are relevant for specific outcomes. In this Review, we examine how the choice of media, cell source, culture environment and storage affects the phenotype and clinical utility of MSC-based products, and discuss the techniques better suited to prime MSCs with specific phenotypes of interest and the need for the continued development of standardized assays that provide quality assurance for clinical-grade MSCs. Bioequivalence between cell products and batches must be investigated rather than assumed, so that the diversity of phenotypes between differing MSC products can be accounted for to identify products with the highest therapeutic potential and to preserve their safety in clinical treatments.

Immunomodulatory Properties of Mesenchymal Stromal Cells: Still Unresolved "Yin and Yang"

Mesenchymal stromal cells (MSC) are mesodermal elements characterized by the ability to differentiate into several types of cells present mainly in connective tissues. They play a key function in tissue homeostasis and repair. Furthermore, they exert a strong effect on both innate and adaptive immune response. The main current of thought considers MSC as strong inhibitors of the immune system. Indeed, the first description of MSC immunomodulation pointed out their inability to induce alloimmune responses and their veto effects on mixed lymphocyte reactions. This inhibition appears to be mediated both by direct MSC interaction with immune cells and by soluble factors. Unfortunately, evidence to support this notion comes almost exclusively from in vitro experiments. In complex experimental systems, it has been shown that MSC can exert immunosuppressive effects also in vivo, either in murine models or in transplanted patients to avoid the graft versus host disease. However, it is still debated how the small number of administered MSC can regulate efficiently a large number of host effector lymphocytes. In addition, some reports in the literature indicate that MSC can trigger rather than inhibit lymphocyte activation when a very low number of MSC are co-cultured with lymphocytes. This would imply that the ratio between the number of MSC and immune cells is a key point to forecast whether MSC will inhibit or activate the immune system. Herein, we discuss the conflicting results reported on the immunomodulatory effects of MSC to define which features are relevant to understand their behavior and cross-talk with immune cells.

Engineered Mesenchymal Stem Cells Expressing Stromal Cell-derived Factor-1 Improve Erectile Dysfunction in Streptozotocin-Induced Diabetic Rats

Effective therapies for erectile dysfunction (ED) associated with diabetes mellitus (DM) are needed. In this study, the effects of stromal cell-derived factor-1 (SDF-1)-expressing engineered mesenchymal stem cells (SDF-1 eMSCs) and the relevant mechanisms in the corpus cavernosum of a streptozotocin (STZ)-induced DM ED rat model were evaluated. In a randomized controlled trial, Sprague–Dawley (SD) rats (n = 48) were divided into four groups (n = 12/group): Normal (control), DM ED (diabetes induced by STZ), DM ED + BM-MSC (treated with bone marrow [BM]-derived MSCs), and DM ED + SDF-1 eMSC (treated with SDF-1-expressing BM-MSCs). After four weeks, intracavernosal pressure (ICP), an indicator of erectile function, was 0.75 ± 0.07 in the normal group, 0.27 ± 0.08 in the DM ED group, 0.42 ± 0.11 in the DM ED + BM-MSC group, and 0.58 ± 0.11 in the DM ED + SDF-1 eMSC group. BM-MSCs, especially SDF-1 eMSCs, improved ED (p < 0.05). SDF-1 eMSC treatment improved the smooth muscle content in the corpus cavernosum (p < 0.05). As SDF-1 expression increased, ED recovery improved. In the SDF-1 eMSC group, levels of neuronal nitric oxide synthase (nNOS) and phosphorylated endothelial NOS (p-eNOS) were higher than those in other groups (p < 0.05). In addition, high stromal cell-derived factor-1 (SDF-1) expression was associated with increased vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) in DM ED rats (p < 0.05). Higher levels of phosphorylated protein kinase B (p-AKT)/protein kinase B (AKT) (p < 0.05) and B-cell lymphoma-2 (Bcl-2) and lower levels of the apoptosis factors Bcl2-associated x (Bax) and caspase-3 were observed in the MSC-treated group than in the DM ED group (p < 0.05). SDF-1 eMSCs showed beneficial effects on recovery from erectile function.

Inertial-Based Filtration Method for Removal of Microcarriers from Mesenchymal Stem Cell Suspensions

Rapidly evolving cell-based therapies towards clinical trials demand alternative approaches for efficient expansion of adherent cell types such as human mesenchymal stem cells (hMSCs). Using microcarriers (100-300 µm) in a stirred tank bioreactor offers considerably enhanced surface to volume ratio of culture environment. However, downstream purification of the harvested cell product needs to be addressed carefully due to distinctive features and fragility of these cell products. This work demonstrates a novel alternative approach which utilizes inertial focusing to separate microcarriers (MCs) from the final cell suspension. First, we systematically investigated MC focusing dynamics inside scaled-up curved channels with trapezoidal and rectangular cross-sections. A trapezoidal spiral channel with ultra-low-slope (Tan(α) = 0.0375) was found to contribute to strong MC focusing (~300 < Re < ~400) while managing high MC volume fractions up to ~1.68%. Accordingly, the high-throughput trapezoidal spiral channel successfully separated MCs from hMSC suspension with total cell yield~94% (after two passes) at a high volumetric flow rate of ~30 mL/min (Re~326.5).

Advantages of Graphene Biosensors for Human Stem Cell Therapy Potency Assays

Regenerative medicine is challenged by the need to conform to rigorous guidelines for establishing safe and effective development and translation of stem cell-based therapies. Counteracting widespread concerns regarding unproven cell therapies, stringent cell-based assays seek not only to avoid harm but also to enhance quality and efficacy. Potency indicates that the cells are functionally fit for purpose before they are administered to the patient. It is a paramount quantitative critical quality attribute serving as a decisive release criterion. Given a broad range of stem cell types and therapeutic contexts the potency assay often comprises one of the most demanding hurdles for release of a cell therapy medicinal product. With need for improved biomarker assessment and expedited measurement, recent advances in graphene-based biosensors suggest that they are poised to be valuable platforms for accelerating potency assay development. Among several potential advantages, they offer versatility for sensitive measurement of a broad range of potential biomarker types, cell biocompatibility for direct measurement, and small sample sufficiency, plus ease of use and point-of-care applicability.

Mesenchymal Stromal Cells: From Discovery to Manufacturing and Commercialization

Over the last decades, mesenchymal stromal cells (MSC) have been the focus of intense research by academia and industry due to their unique features. MSC can be easily isolated and expanded through in vitro culture by taking full advantage of their self-renewing capacity. In addition, MSC exert immunomodulatory effects and can be differentiated into various lineages, which makes them highly attractive for clinical applications in cell-based therapies. In this review, we attempt to provide a brief historical overview of MSC discovery, characterization, and the first clinical studies conducted. The current MSC manufacturing platforms are reviewed with special attention regarding the use of bioreactors for the production of GMP-compliant clinically relevant cell numbers. The first commercial MSC-based products are also addressed, as well as the remaining challenges to the widespread use of MSC-derived products.

The biological basis for concentrated iliac crest aspirate to enhance core decompression in the treatment of osteonecrosis

Core decompression is a surgical procedure that is capable of salvaging the patient's own natural joint, if the operation is performed in the early stages of osteonecrosis, in which the articular surface has not collapsed. The addition of concentrated cells, aspirated from the iliac crest, to the core tract has been shown to enhance the viability of the femoral head, although large, prospective, randomized, blinded multicentre studies are lacking. The rationale for adding these cells to the core decompression tract is to provide osteoprogenitor and vascular progenitor cells to the area of decompressed dead bone, in order to facilitate tissue regeneration and repair. It has become increasingly evident that vast discrepancies exist in different series in regard to the criteria for patient selection, the surgical technique of core decompression, the methods for harvesting, processing, and injecting the cells, and the methodology for determining success or failure in a specific patient cohort. This paper reviews the salient points relevant to the treatment of osteonecrosis by core decompression with addition of concentrated iliac crest aspirates and poses important questions regarding the future successful application of this technique.