Risk factors in the development of stem cell therapy

New therapeutic approach with extracellular vesicles from stem cells for interstitial cystitis/bladder pain syndrome

Interstitial cystitis/bladder pain syndrome (IC/BPS) is a debilitating chronic disorder characterized by suprapubic pain and urinary symptoms such as urgency, nocturia, and frequency. The prevalence of IC/BPS is increasing as diagnostic criteria become more comprehensive. Conventional pharmacotherapy against IC/BPS has shown suboptimal effects, and consequently, patients with end-stage IC/BPS are subjected to surgery. The novel treatment strategies should have two main functions, anti-inflammatory action and the regeneration of glycosaminoglycan and urothelium layers. Stem cell therapy has been shown to have dual functions. Mesenchymal stem cells (MSCs) are a promising therapeutic option for IC/BPS, but they come with several shortcomings, such as immune activation and tumorigenicity. MSC-derived extracellular vesicles (MSC-EVs) hold numerous therapeutic cargos and are thus a viable cell-free therapeutic option. In this review, we provide a brief overview of IC/BPS pathophysiology and limitations of the MSC-based therapies. Then we provide a detailed explanation and discussion of therapeutic applications of EVs in IC/BPS as well as the possible mechanisms. We believe our review will give an insight into the strengths and drawbacks of EV-mediated IC/BPS therapy and will provide a basis for further development.

New therapeutic approach with extracellular vesicles from stem cells for interstitial cystitis/bladder pain syndrome

Interstitial cystitis/bladder pain syndrome (IC/BPS) is a debilitating chronic disorder characterized by suprapubic pain and urinary symptoms such as urgency, nocturia, and frequency. The prevalence of IC/BPS is increasing as diagnostic criteria become more comprehensive. Conventional pharmacotherapy against IC/BPS has shown suboptimal effects, and consequently, patients with end-stage IC/BPS are subjected to surgery. The novel treatment strategies should have two main functions, anti-inflammatory action and the regeneration of glycosaminoglycan and urothelium layers. Stem cell therapy has been shown to have dual functions. Mesenchymal stem cells (MSCs) are a promising therapeutic option for IC/BPS, but they come with several shortcomings, such as immune activation and tumorigenicity. MSC-derived extracellular vesicles (MSC-EVs) hold numerous therapeutic cargos and are thus a viable cell-free therapeutic option. In this review, we provide a brief overview of IC/BPS pathophysiology and limitations of the MSC-based therapies. Then we provide a detailed explanation and discussion of therapeutic applications of EVs in IC/BPS as well as the possible mechanisms. We believe our review will give an insight into the strengths and drawbacks of EV-mediated IC/BPS therapy and will provide a basis for further development. [BMB Reports 2022; 55(5): 205-212].

In vitro study of the mesenchymal stem cells-conditional media role in skin wound healing process: A systematic review

Mesenchymal stromal cell (MSC)-conditioned medium (CM) offers a potential opportunity in the skin wound healing treatment. In this systematic review, an overview of the knowledge on this topic has been provided. A multistep search of the PubMed, Scopus and Science Direct database has been performed to identify papers on MSCs-conditional media used in skin wound healing. Eligibility checks were performed based upon predefined selection criteria. Of the 485 articles initially identified, consequently, only 96 articles apparently related to MSC-conditional media were initially assessed for eligibility. Finally, the 32 articles, strictly regarding the in vitro use of MSCs-conditional media in skin wounds, were analysed. The information analysed highlights the efficacy of MSCs-conditional media on skin wound healing in vitro models. The outcome of this review may be used to guide pre-clinical and clinical studies on the role of MSCs-conditional media in skin wound healing.

GelMA Hydrogel Reinforced with 3D Printed PEGT/PBT Scaffolds for Supporting Epigenetically-Activated Human Bone Marrow Stromal Cells for Bone Repair

Epigenetic approaches using the histone deacetylase 2 and 3 inhibitor-MI192 have been reported to accelerate stem cells to form mineralised tissues. Gelatine methacryloyl (GelMA) hydrogels provide a favourable microenvironment to facilitate cell delivery and support tissue formation. However, their application for bone repair is limited due to their low mechanical strength. This study aimed to investigate a GelMA hydrogel reinforced with a 3D printed scaffold to support MI192-induced human bone marrow stromal cells (hBMSCs) for bone formation. Cell culture: The GelMA (5 wt%) hydrogel supported the proliferation of MI192-pre-treated hBMSCs. MI192-pre-treated hBMSCs within the GelMA in osteogenic culture significantly increased alkaline phosphatase activity (p ≤ 0.001) compared to control. Histology: The MI192-pre-treated group enhanced osteoblast-related extracellular matrix deposition and mineralisation (p ≤ 0.001) compared to control. Mechanical testing: GelMA hydrogels reinforced with 3D printed poly(ethylene glycol)-terephthalate/poly(butylene terephthalate) (PEGT/PBT) scaffolds exhibited a 1000-fold increase in the compressive modulus compared to the GelMA alone. MI192-pre-treated hBMSCs within the GelMA–PEGT/PBT constructs significantly enhanced extracellular matrix collagen production and mineralisation compared to control (p ≤ 0.001). These findings demonstrate that the GelMA–PEGT/PBT construct provides enhanced mechanical strength and facilitates the delivery of epigenetically-activated MSCs for bone augmentation strategies.

Peripheral Blood Mononuclear Cells Regulate Differentially Expressed Proteins in the Proximal Sciatic Nerve of Rats after Transection Anastomosis

Peripheral nerve injury (PNI) is a common disease that causes the partial loss of sensory, exercise, and autonomic nervous function. In clinical practice, accurate end-to-end neurorrhaphy of the epineurium without tension is the ideal treatment when there is no nerve defect. We have confirmed that peripheral blood mononuclear cells (PBMCs) can effectively improve nerve regeneration and functional recovery after PNI. However, the global protein profile and signaling conduction pathways regulated by PBMCs remain unclear. This study employed the transection anastomosis model to detect the walking track analysis, gastrocnemius wet weight rate, and morphological examination in order to validate the effect of PBMCs on sciatic nerve injury in rats. Results showed that PBMCs improved nerve regeneration after sciatic nerve dissociation and anastomosis in rats, which reflected in the improvement of the sciatic nerve function index, wet weight rate of gastrocnemius muscles, muscle fiber structure, and the number of axons. We then used TMT labeling quantitative proteomics to explore the underlying mechanism by which PBMCs ameliorated sciatic nerve injury. Results showed that PBMCs regulated 40 differential proteins and the regulated proteins were primarily involved in the complement and coagulation cascade pathways, the notch signaling pathway, the renin angiotensin system, DNA replication, histidine metabolism, β-alanine metabolism, and other types of O-glycan biosynthesis. Immunohistochemical results supported our findings on the changes in expression of Kininogen 1 and Psen1, the relationships between PNI and the notch pathway and the complement and coagulation level pathways.

An ECM-Mimetic Hydrogel to Promote the Therapeutic Efficacy of Osteoblast-Derived Extracellular Vesicles for Bone Regeneration

The use of extracellular vesicles (EVs) is emerging as a promising acellular approach for bone regeneration, overcoming translational hurdles associated with cell-based therapies. Despite their potential, EVs short half-life following systemic administration hinders their therapeutic efficacy. EVs have been reported to bind to extracellular matrix (ECM) proteins and play an essential role in matrix mineralisation. Chitosan and collagen type I are naturally-derived pro-osteogenic biomaterials, which have been demonstrated to control EV release kinetics. Therefore, this study aimed to develop an injectable ECM-mimetic hydrogel capable of controlling the release of osteoblast-derived EVs to promote bone repair. Pure chitosan hydrogels significantly enhanced compressive modulus (2.48-fold) and osteogenic differentiation (3.07-fold), whilst reducing gelation times (2.09-fold) and proliferation (2.7-fold) compared to pure collagen gels (p ≤ 0.001). EV release was strongly associated with collagen concentration (R² > 0.94), where a significantly increased EV release profile was observed from chitosan containing gels using the CD63 ELISA (p ≤ 0.001). Hydrogel-released EVs enhanced human bone marrow stromal cells (hBMSCs) proliferation (1.12-fold), migration (2.55-fold), and mineralisation (3.25-fold) compared to untreated cells (p ≤ 0.001). Importantly, EV-functionalised chitosan-collagen composites significantly promoted hBMSCs extracellular matrix mineralisation when compared to the EV-free gels in a dose-dependent manner (p ≤ 0.001). Taken together, these findings demonstrate the development of a pro-osteogenic thermosensitive chitosan-collagen hydrogel capable of enhancing the therapeutic efficacy of osteoblast-derived EVs as a novel acellular tool for bone augmentation strategy.

Efficacy and safety of mesenchymal stem cells in the treatment of systemic sclerosis: a systematic review and meta-analysis

Background

Systemic sclerosis (SSc) is an autoimmune disease with high morbidity and mortality characterized by fibrosis of the skin and internal organs. Some studies have investigated the use of stem cells to treat SSc. Herein, a systematic review and meta-analysis was conducted to determine the efficacy and safety of mesenchymal stem cells (MSCs) in the treatment of SSc.

Methods

PubMed, Embase, Cochrane Library, Web of Science, OVID, China National Knowledge Infrastructure and Wanfang databases were searched up to February 1, 2021. Literature screening, data extraction and quality assessment were conducted independently by two researchers in according to the inclusion and exclusion criteria. The discrepancies were resolved by a third researcher.

Results

A total of 9 studies encompassing 133 SSc patients were included in the study. Compared to the baseline after treatment with MSCs: 1. The modified Rodnan skin score (mRSS) was significantly reduced in patients with SSc (P < 0.00001). 2. MSCs decreased the number of digital ulcer, mouth handicap scale, and visual analog scale of hand pain in SSc patients (P = 0.0007 and P = 0.03, respectively). 3. No statistical differences were detected in Raynaud's condition score and Cochin hand function scale score at 6 months of MSCs therapy (P = 0.5 and P = 0.62). 4. After 12 months of follow-up, MSCs improve carbon monoxide diffusing capacity and forced vital capacity of SSc patients (P < 0.05). 5. Overall, MSCs application was safe; a few cases exhibited swelling at the injection site, diarrhea and arthralgia, which had self-recovery, and no severe adverse events occurred in the included trials.

Conclusions

MSC therapy improves the degree of skin thickening, lung function, and mouth opening and relieves finger ulcers and pain in patients with SSc without severe adverse events. Thus, MSCs or MSCs combined with plasma and traditional medicine might be an effective and promising treatment of SSc patients.

PROSPERO registration number: CRD42020200350

Brachial plexus bridging with specific extracellular matrix modified chitosan/silk scaffold: a new expand of tissue engineered nerve graft

OBJECTIVE

Brachial plexus injuries result in serious dysfunction and are currently treated using autologous nerve graft (autograft) transplantation. With the development of tissue engineering, tissue engineered nerve grafts (TENGs) have emerged as promising alternatives to autografts but have not yet been widely applied to the treatment of brachial plexus injuries. Herein, we developed a TENG modified with extracellular matrix (ECM) generated by skin-derived precursor Schwann cells (SKP-SCs) and expand its application in upper brachial plexus defects in rats.

APPROACH

SKP-SCs were co-cultured with chitosan neural conduits or silk fibres and subjected to decellularization treatment. Ten bundles of silk fibres (five fibres per bundle) were placed into a conduit to obtain the TENG, which was used to bridge an 8 mm gap in the upper brachial plexus. The efficacy of this treatment was examined for TENG-, autograft- and scaffold-treated groups at several times after surgery using immunochemical staining, behavioural tests, electrophysiological measurements, and electron microscopy.

MAIN RESULTS

Histological analysis conducted two weeks after surgery showed that compared to scaffold bridging, TENG treatment enhanced the growth of regenerating axons. Behavioural tests conducted four weeks after surgery showed that TENG-treated rats performed similarly to autograft-treated ones, with a significant improvement observed in both cases compared with the scaffold treatment group. Electrophysiological and retrograde tracing characterisations revealed that the target muscles were reinnervated in both TENG and autograft groups, while transmission electron microscopy and immunohistochemical staining showed the occurrence of the superior myelination of regenerated axons in these groups.

SIGNIFICANCE

Treatment with the developed TENG allows the effective bridging of proximal nerve defects in the upper extremities, and the obtained results provide a theoretical basis for clinical transformation to expand the application scope of TENGs.

Stem cell differentiation with consistent lineage commitment induced by a flash of ultrafast-laser activation in vitro and in vivo

Recent technological advancements on stem cell differentiation induction have been making great progress in stem cell research, regenerative medicine, and therapeutic applications. However, the risk of off-target differentiation limits the wide application of stem cell therapy strategies. Here, we report a non-invasive all-optical strategy to induce stem cell differentiation in vitro and in vivo that activates individual target stem cells in situ by delivering a transient 100-ms irradiation of a tightly focused femtosecond laser to a submicron cytoplasmic region of primary adipose-derived stem cells (ADSCs). The ADSCs differentiate to osteoblasts with stable lineage commitment that cannot further transdifferentiate because of simultaneous initiation of multiple signaling pathways through specific Ca²⁺ kinetic patterns. This method can work in vivo to direct mouse cerebellar granule neuron progenitors to granule neurons in intact mouse cerebellums through the skull. Hence, this optical method without any genetic manipulations or exogenous biomaterials holds promising potential in biomedical research and cell-based therapies.

Next-Generation Sequencing of Circular RNAs Reveals the Molecular Mechanisms of Chondrogenic Differentiation in Human Adipose-derived Stem Cells

Adipose-derived stem cells are one of the potential sources of cells for the treatment of cartilage defects. This study aimed to investigate the molecular mechanisms that account for the chondrogenic differentiation of human adipose-derived stem cells (hADSCs). We employed integrin β1 (ITGB1) overexpression to induce chondrogenic differentiation of hADSCs. Next-generation sequencing was used to determine the mRNAs and circular RNAs (circRNAs) expression profiles in ITGB1-overexpresing and negative control cells. The potential functions of differentially expressed mRNAs were analyzed using the Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) analyses. Moreover, differentially expressed circRNAs with the greatest fold change were validated by polymerase chain reaction (PCR), Sanger sequencing, and quantitative real-time PCR (qRT-PCR). These three circRNAs and their downstream microRNAs and mRNAs were used to construct a circRNA-microRNA-mRNA interaction network. The results showed that we identified 713 differentially expressed circRNAs (150 upregulated and 563 downregulated in ITGB1-overexpressing hADSCs versus negative control cells, respectively). Meanwhile, 2383 mRNAs were differentially expressed between two groups (1672 upregulated and 711 downregulated in ITGB1-overexpressing cells compared with the negative control cells). The GO and KEGG analysis results showed that the differentially expressed mRNAs were enriched in biological processes, cellular components, and molecular functions, especially in the phosphatidylinositol 3-kinase (PI3K)-AKT and mitogen-activated protein kinase signaling pathways. Three differentially expressed circRNAs, including hsa_circ_0071127, hsa_circ_0008637, and hsa_circ_0020028, were validated by qRT-PCR. Moreover, the circRNA-microRNA-mRNA network predicted that fibroblast growth factor 2 (FGF2) was a common node regulated by these three circRNAs through several microRNAs, including miR-195-3p, miR-205-3p, and miR-152-3p. We further found that the knockdown of hsa_circ_0020028, but not the two other circRNAs, significantly reduced FGF2 mRNA expression in hADSCs. Furthermore, the knockdown of hsa_circ_0020028 significantly inhibited the protein expression of FGF2, chondrogenic differentiation markers (COL II, aggrecan, and SOX9), and PI3K/AKT signaling in ITGB1-overexpressing hADSCs. This study uncovered the differentially expressed mRNA and circRNA profiles in the chondrogenic differentiation of hADSCs induced by ITGB1 overexpression. Our findings demonstrate that hsa_circ_0020028 regulates the ITGB1 overexpression-mediated chondrogenic differentiation of hADSCs through regulation of FGF2-related signaling pathways.

Stem Cell Therapy: From Idea to Clinical Practice

Regenerative medicine is a new and promising mode of therapy for patients who have limited or no other options for the treatment of their illness. Due to their pleotropic therapeutic potential through the inhibition of inflammation or apoptosis, cell recruitment, stimulation of angiogenesis, and differentiation, stem cells present a novel and effective approach to several challenging human diseases. In recent years, encouraging findings in preclinical studies have paved the way for many clinical trials using stem cells for the treatment of various diseases. The translation of these new therapeutic products from the laboratory to the market is conducted under highly defined regulations and directives provided by competent regulatory authorities. This review seeks to familiarize the reader with the process of translation from an idea to clinical practice, in the context of stem cell products. We address some required guidelines for clinical trial approval, including regulations and directives presented by the Food and Drug Administration (FDA) of the United States, as well as those of the European Medicine Agency (EMA). Moreover, we review, summarize, and discuss regenerative medicine clinical trial studies registered on the Clinicaltrials.gov website.

Lipopolysaccharide increases exosomes secretion from endothelial progenitor cells by toll-like receptor 4 dependent mechanism

Endothelial progenitor cells (EPCs) can exert angiogenic effects by a paracrine mechanism, where exosomes work as an important mediator. Recent studies reported functional expression of toll-like receptor (TLR) 4 on human EPCs and dose-dependent effects of lipopolysaccharide (LPS) on EPC angiogenic properties. To study on the effects of TLR4/LPS signaling on EPC-derived exosomes (Exo) and involved mechanisms, we investigated the effect of LPS on exosomes secretion from human EPC and tested Exo functions by senescence-associated β-galactosidase activity assay and reactive oxygen species (ROS) related H₂ DCF-DA assay. To clarify the mechanism, we examined the changes in intracellular calcium levels and multivesicular bodies (MVBs) development in EPC. We employed the inhibitors of the plasma membrane Ca ²⁺ -ATPase (PMCA), endoplasmic reticulum Ca ²⁺ -ATPase (ERCA), PLC-IP₃ pathway and store-operated calcium entry to assess the effects of LPS on calcium signalings which critical for exosome secretion. LPS induced the release of Exo in a TLR4-dependent manner in vitro, which effect can be partly abrogated by the membrane-permeable IP ₃ R antagonist, 2-aminoethyl diphenylborinate (2-APB), but not PLC inhibitor, U-73122. The LPS can significantly delay the fallback of [Ca ²⁺ ]_i after isolating the cellular PMCA activity, and disturb PMCA 1/4 expression. The distribution of elevated intracellular calcium seemed coincident with the development of MVBs. Furthermore, the LPS-induced Exo maintained valid anti-oxidation/senescence properties. The PMCA and ER Ca ²⁺ release mechanism may contribute to the pro-exosomal effects of LPS on EPC, which is valuable for potential pro-regenerative application in future. This article is protected by copyright. All rights reserved.

Fetal lung regeneration using stem cell-derived extracellular vesicles: A new frontier for pulmonary hypoplasia secondary to congenital diaphragmatic hernia

The poor outcomes of babies with congenital diaphragmatic hernia (CDH) are directly related to pulmonary hypoplasia, a cosndition characterized by impaired lung development. Although the pathogenesis of pulmonary hypoplasia is not fully elucidated, there is now evidence that CDH patients have missing or dysregulated microRNAs (miRNAs) that regulate lung development. A prenatal therapy that supplements these missing/dysregulated miRNAs could be a strategy to rescue normal lung development. Extracellular vesicles (EVs), also known as exosomes when of small dimensions, are lipid-bound nanoparticles that can transfer their heterogeneous cargo (proteins, lipids, small RNAs) to target cells to induce biological responses. Herein, we review all studies that show evidence for stem cell-derived EVs as a regenerative therapy to rescue normal development in CDH fetal lungs. Particularly, we report studies showing that administration of EVs derived from amniotic fluid stem cells (AFSC-EVs) to models of pulmonary hypoplasia promotes fetal lung growth and maturation via transfer of miRNAs that are known to regulate lung developmental processes. We also describe that stem cell-derived EVs exert effects on vascular remodeling, thus possibly preventing postnatal pulmonary hypertension. Finally, we discuss future perspectives and challenges to translate this promising stem cell EV-based therapy to clinical practice. This article is protected by copyright. All rights reserved.

Application of Wharton jelly-derived mesenchymal stem cells in patients with pulmonary fibrosis

Pulmonary fibrosis is a devastating disease that eventually leads to death and respiratory failure. Despite the wide range of drugs, including corticosteroids, endothelin antagonist, and pirfenidone, there is no effective treatment, and the only main goal of treatment is to alleviate the symptoms as much as possible to slow down the progression of the disease and improve the quality of life. Lung transplantation may be a treatment option for a few people if pulmonary fibrosis develops and there is no established treatment. Pulmonary fibrosis caused by the COVID19 virus is another problem that we face in most patients despite the efforts of the international medical communities. Therefore, achieving alternative treatment for patients is a great success. Today, basic research using stem cells on pulmonary fibrosis has published promising results. New stem cell-based therapies can be helpful in patients with pulmonary fibrosis. Wharton jelly-derived mesenchymal stem cells are easily isolated in large quantities and made available for clinical trials without causing ethical problems. These cells have higher flexibility and proliferation potential than other cells isolated from different sources and differentiated into various cells in laboratory environments. More clinical trials are needed to determine the safety and efficacy of these cells. This study will investigate the cellular and molecular mechanisms and possible effects of Wharton jelly-derived mesenchymal stem cells in pulmonary fibrosis.

Biomolecule-Mediated Therapeutics of the Dentin–Pulp Complex: A Systematic Review

The aim of this systematic review was to evaluate the application of potential therapeutic signaling molecules on complete dentin-pulp complex and pulp tissue regeneration in orthotopic and ectopic animal studies. A search strategy was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement in the MEDLINE/PubMed database. Animal studies evaluating the application of signaling molecules to pulpectomized teeth for pulp tissue or dentin-pulp complex regeneration were included. From 2530 identified records, 18 fulfilled the eligibility criteria and were subjected to detailed qualitative analysis. Among the applied molecules, basic fibroblast growth factor, vascular endothelial growth factor, bone morphogenetic factor-7, nerve growth factor, and platelet-derived growth factor were the most frequently studied. The clinical, radiographical and histological outcome measures included healing of periapical lesions, root development, and apical closure, cellular recolonization of the pulp space, ingrowth of pulp-like connective tissue (vascularization and innervation), mineralized dentin-like tissue formation along the internal dentin walls, and odontoblast-like cells in contact with the internal dentin walls. The results indicate that signaling molecules play an important role in dentin/pulp regeneration. However, further studies are needed to determine a more specific subset combination of molecules to achieve greater efficiency towards the desired tissue engineering applications.

Decellularized Dental Pulp, Extracellular Vesicles, and 5-Azacytidine: A New Tool for Endodontic Regeneration

Dental pulp is a major component of the dental body that serves to maintain the tooth life and function. The aim of the present work was to develop a system that functions as a growth-permissive microenvironment for dental pulp regeneration using a decellularized dental pulp (DDP) matrix, 5-Aza-2′-deoxycytidine (5-Aza), and Extracellular Vesicles (EVs) derived from human Dental Pulp Stem Cells (hDPSCs). Human dental pulps extracted from healthy teeth, scheduled to be removed for orthodontic purpose, were decellularized and then recellularized with hDPSCs. The hDPSCs were seeded on DDP and maintained under different culture conditions: basal medium (CTRL), EVs, 5-Aza, and EVs+-5-Aza. Immunofluorescence staining and Western blot analyses were performed to evaluate the proteins’ expression related to dentinogenesis, such as ALP, RUNX2, COL1A1, Vinculin, DMP1, and DSPP. Protein contents found in the DDP recellularized with hDPSCs were highly expressed in samples co-treated with EVs and 5-Aza compared to other culture conditions. This study developed a DDP matrix loaded by hDPSCs in co-treatment with EVs, which might enhance the dentinogenic differentiation with a high potentiality for endodontic regeneration.

Transplantation of decellularised human amniotic membranes seeded with mesenchymal stem cell-educated macrophages into animal models

The reconstruction of chronic skin wounds remains a public health challenge in dermatology. Precisely controlling and monitoring the wound-healing process should result in enhanced outcomes for the patient. Cell-based therapies have shown great potential in medicine due to their immunomodulatory and healing properties. Herein, we produced activated macrophages by treating circulating monocytes with mesenchymal stem cell (MSC) supernatant. We also demonstrated the critical role of activated macrophages transplantation using amniotic membranes in accelerating wound healing in an animal wound model. The activated macrophages not only exhibited immunomodulatory cytokines like transforming growth factorβ (TGFβ) and interleukin 10 (and IL10) secretion but also showed attachment and proliferation ability on the amniotic membrane scaffold. Moreover, MSCs supernatant-treated cells also displayed significant ARG1, CD206, and IL 10 genes expression. Inspired by the in vitro results, we examined the in vivo therapeutic efficacy of the activated macrophage transplantation using an acellular amniotic membrane carrier in a full-thickness cutaneous wound model. The wound healing rate was significant in the group treated with macrophages generated via mesenchymal cell therapy seeded human amniotic membrane. There was less scarring in the wound sites after placing cell-scaffold constructs in the wound sites in the animal models. Overall, macrophages stimulated with mesenchymal cells' supernatant exhibited improved healing processes in incisional wounds by decreasing the inflammatory phase, increasing angiogenesis, and reducing scar tissue development.

A2B5-positive oligodendrocyte precursor cell transplantation improves neurological deficits in rats following spinal cord contusion associated with changes in expression of factors involved in the Notch signaling pathway

BACKGROUND

Oligodendrocyte precursor cells (OPCs) are myelinated glial cells of the central nervous system (CNS), able to regenerate oligodendrocytes and myelin. This study aimed to elucidate the effect of A2B5-positive (A2B5+) OPC transplantation in rats with spinal cord contusion (SCC) and to investigate changes in expression of various factors involved in the Notch signaling pathway after OPC transplantation.

METHODS

OPCs were obtained from induced pluripotent stem cells (iPSCs) originating from mouse embryo fibroblasts (MEFs). After identification of iPSCs and iPSC-derived OPCs, A2B5+ OPCs were transplanted into the injured site of rats with SCC one week after SCC insult. Behavioral tests evaluated motor and sensory function 7 days after OPC transplantation. Real-time quantitative polymerase chain reaction (RT-qPCR) determined the expression of various cytokines related to the Notch signaling pathway after OPC transplantation.

RESULTS

IPSC-derived OPCs were successfully generated from MEFs, as indicated by positive immunostaining of A2B5, PDGFα and NG2. Further differentiation of OPCs was identified by immunostaining of Olig2, Sox10, Nkx2.2, O4, MBP and GFAP. Importantly, myelin formation was significantly enhanced in the SCC+ OPC group and SCI-induced motor and sensory dysfunction was largely alleviated by A2B5+ OPC transplantation. Expression of factors involved in the Notch signaling pathway (Notch-1, Numb, SHARP1 and NEDD4) was significantly increased after OPC transplantation.

CONCLUSIONS

A2B5+ OPC transplantation attenuates motor and sensory dysfunction in SCC rats by promoting myelin formation, which may be associated with change in expression of factors involved in the Notch signaling pathway.

Stem Cell Transplantation Therapy and Neurological Disorders: Current Status and Future Perspectives

Neurodegenerative diseases are a global health issue with inadequate therapeutic options and an inability to restore the damaged nervous system. With advances in technology, health scientists continue to identify new approaches to the treatment of neurodegenerative diseases. Lost or injured neurons and glial cells can lead to the development of several neurological diseases, including Parkinson's disease, stroke, and multiple sclerosis. In recent years, neurons and glial cells have successfully been generated from stem cells in the laboratory utilizing cell culture technologies, fueling efforts to develop stem cell-based transplantation therapies for human patients. When a stem cell divides, each new cell has the potential to either remain a stem cell or differentiate into a germ cell with specialized characteristics, such as muscle cells, red blood cells, or brain cells. Although several obstacles remain before stem cells can be used for clinical applications, including some potential disadvantages that must be overcome, this cellular development represents a potential pathway through which patients may eventually achieve the ability to live more normal lives. In this review, we summarize the stem cell-based therapies that have been explored for various neurological disorders, discuss the potential advantages and drawbacks of these therapies, and examine future directions for this field.

Controlled Release of Epigenetically-Enhanced Extracellular Vesicles from a GelMA/Nanoclay Composite Hydrogel to Promote Bone Repair

Extracellular vesicles (EVs) have garnered growing attention as promising acellular tools for bone repair. Although EVs' potential for bone regeneration has been shown, issues associated with their therapeutic potency and short half-life in vivo hinders their clinical utility. Epigenetic reprogramming with the histone deacetylase inhibitor Trichostatin A (TSA) has been reported to promote the osteoinductive potency of osteoblast-derived EVs. Gelatin methacryloyl (GelMA) hydrogels functionalised with the synthetic nanoclay laponite (LAP) have been shown to effectively bind, stabilise, and improve the retention of bioactive factors. This study investigated the potential of utilising a GelMA-LAP hydrogel to improve local retention and control delivery of epigenetically enhanced osteoblast-derived EVs as a novel bone repair strategy. LAP was found to elicit a dose-dependent increase in GelMA compressive modulus and shear-thinning properties. Incorporation of the nanoclay was also found to enhance shape fidelity when 3D printed compared to LAP-free gels. Interestingly, GelMA hydrogels containing LAP displayed increased mineralisation capacity (1.41-fold) (p ≤ 0.01) over 14 days. EV release kinetics from these nanocomposite systems were also strongly influenced by LAP concentration with significantly more vesicles being released from GelMA constructs as detected by a CD63 ELISA (p ≤ 0.001). EVs derived from TSA-treated osteoblasts (TSA-EVs) enhanced proliferation (1.09-fold), migration (1.83-fold), histone acetylation (1.32-fold) and mineralisation (1.87-fold) of human bone marrow stromal cells (hBMSCs) when released from the GelMA-LAP hydrogel compared to the untreated EV gels (p ≤ 0.01). Importantly, the TSA-EV functionalised GelMA-LAP hydrogel significantly promoted encapsulated hBMSCs extracellular matrix collagen production (≥1.3-fold) and mineralisation (≥1.78-fold) in a dose-dependent manner compared to untreated EV constructs (p ≤ 0.001). Taken together, these findings demonstrate the potential of combining epigenetically enhanced osteoblast-derived EVs with a nanocomposite photocurable hydrogel to promote the therapeutic efficacy of acellular vesicle approaches for bone regeneration.

Stem Cell Mimicking Nanoencapsulation for Targeting Arthritis

Mesenchymal stem cells (MSCs) are considered a promising regenerative therapy due to their ability to migrate toward damaged tissues. The homing ability of MSCs is unique compared with that of non-migrating cells and MSCs are considered promising therapeutic vectors for targeting major cells in many pathophysiological sites. MSCs have many advantages in the treatment of malignant diseases, particularly rheumatoid arthritis (RA). RA is a representative autoimmune disease that primarily affects joints, and secreted chemokines in the joints are well recognized by MSCs following their migration to the joints. Furthermore, MSCs can regulate the inflammatory process and repair damaged cells in the joints. However, the functionality and migration ability of MSCs injected in vivo still show insufficient. The targeting ability and migration efficiency of MSCs can be enhanced by genetic engineering or modification, eg, overexpressing chemokine receptors or migration-related genes, thus maximizing their therapeutic effect. However, there are concerns about genetic changes due to the increased probability of oncogenesis resulting from genome integration of the viral vector, and thus, clinical application is limited. Furthermore, it is suspected that administering MSCs can promote tumor growth and metastasis in xenograft and orthotopic models. For this reason, MSC mimicking nanoencapsulations are an alternative strategy that does not involve using MSCs or bioengineered MSCs. MSC mimicking nanoencapsulations consist of MSC membrane-coated nanoparticles, MSC-derived exosomes and artificial ectosomes, and MSC membrane-fused liposomes with natural or genetically engineered MSC membranes. MSC mimicking nanoencapsulations not only retain the targeting ability of MSCs but also have many advantages in terms of targeted drug delivery. Specifically, MSC mimicking nanoencapsulations are capable of encapsulating drugs with various components, including chemotherapeutic agents, nucleic acids, and proteins. Furthermore, there are fewer concerns over safety issues on MSC mimicking nanoencapsulations associated with mutagenesis even when using genetically engineered MSCs, because MSC mimicking nanoencapsulations use only the membrane fraction of MSCs. Genetic engineering is a promising route in clinical settings, where nano-encapsulated technology strategies are combined. In this review, the mechanism underlying MSC homing and the advantages of MSC mimicking nanoencapsulations are discussed. In addition, genetic engineering of MSCs and MSC mimicking nanoencapsulation is described as a promising strategy for the treatment of immune-related diseases.

Pre-clinical study of human umbilical cord mesenchymal stem cell transplantation for the treatment of traumatic brain injury: safety evaluation from immunogenic and oncogenic perspectives

Stem cell therapy is a promising strategy for the treatment of traumatic brain injury (TBI). However, animal experiments are needed to evaluate safety; in particular, to examine the immunogenicity and tumorigenicity of human umbilical cord mesenchymal stem cells (huMSCs) before clinical application. In this study, huMSCs were harvested from human amniotic membrane and umbilical cord vascular tissue. A rat model of TBI was established using the controlled cortical impact method. Starting from the third day after injury, the rats were injected with 10 μL of 5 × 10⁶/mL huMSCs by cerebral stereotaxis or with 500 μL of 1 × 10⁶/mL huMSCs via the tail vein for 3 successive days. huMSC transplantation decreased the serum levels of proinflammatory cytokines in rats with TBI and increased the serum levels of anti-inflammatory cytokines, thereby exhibiting good immunoregulatory function. The transplanted huMSCs were distributed in the liver, lung and brain injury sites. No abnormal proliferation or tumorigenesis was found in these organs up to 12 months after transplantation. The transplanted huMSCs negligibly proliferated in vivo, and apoptosis was gradually observed at later stages. These findings suggest that huMSC transplantation for the treatment of traumatic brain injury displays good safety. In addition, huMSCs exhibit good immunoregulatory function, which can help prevent and reduce secondary brain injury caused by the rapid release of inflammatory factors after TBI. This study was approved by the Ethics Committee of Wuhan General Hospital of PLA (approval No. 20160054) on November 1, 2016.

Electrically controlled mRNA delivery using a polypyrrole-graphene oxide hybrid film to promote osteogenic differentiation of human mesenchymal stem cells

Direct messenger ribonucleic acid (mRNA) delivery to target cells or tissues has revolutionized the field of biotechnology. However, the applicability of regenerative medicine is limited by the technical difficulties of various mRNA-loaded nanocarriers. Herein, we report a new conductive hybrid film that could guide osteogenic differentiation of human adipose-derived mesenchymal stem cells (hADMSCs) via electrically controlled mRNA delivery. To find optimal electrical conductivity and mRNA-loading capacity, the polypyrrole-graphene oxide (PPy-GO) hybrid film was electropolymerized on indium tin oxide substrates. We found that the fluorescein sodium salt, a molecule partially mimicking the physical and chemical properties of mRNAs, can be effectively absorbed and released by electrical stimulation (ES). The hADMSCs cultivated on the PPy-GO hybrid film loaded with pre-osteogenic mRNAs showed the highest osteogenic differentiation under electrical stimulation. This platform can load various types of RNAs thus highly promising as a new nucleic acid delivery tool for the development of stem cell-based therapeutics.

ELECTRONIC SUPPLEMENTARY MATERIAL

Supplementary material (electrochemical and FT-IR analysis on the film, additional SEM, AFM and C-AFM images of the film, optical and fluorescence images of cells, and the primers used for RT-qPCR analysis) is available in the online version of this article at 10.1007/s12274-022-4613-y.

Cardiovascular Regeneration via Stem Cells and Direct Reprogramming: A Review

Despite recent advancements in treatment strategies, cardiovascular disease such as heart failure remains a significant source of global mortality. Stem cell technology and cellular reprogramming are rapidly growing fields that will continue to prove useful in cardiac regenerative therapeutics. This review provides information on the role of human pluripotent stem cells (hPSCs) in cardiac regeneration and discusses the practical applications of hPSC-derived cardiomyocytes (CMCs). Moreover, we discuss the practical applications of hPSC-derived CMCs while outlining the relevance of directly-reprogrammed CMCs in regenerative medicine. This review critically summarizes the most recent advances in the field will help to guide future research in this developing area.

Cardiovascular disease (CVD) is the leading causes of morbidity and death globally. In particular, a heart failure remains a major problem that contributes to global mortality. Considerable advancements have been made in conventional pharmacological therapies and coronary intervention surgery for cardiac disorder treatment. However, more than 15% of patients continuously progress to end-stage heart failure and eventually require heart transplantation. Over the past year, numerous numbers of protocols to generate cardiomyocytes (CMCs) from human pluripotent stem cells (hPSCs) have been developed and applied in clinical settings. Number of studies have described the therapeutic effects of hPSCs in animal models and revealed the underlying repair mechanisms of cardiac regeneration. In addition, biomedical engineering technologies have improved the therapeutic potential of hPSC-derived CMCs in vivo. Recently substantial progress has been made in driving the direct differentiation of somatic cells into mature CMCs, wherein an intermediate cellular reprogramming stage can be bypassed. This review provides information on the role of hPSCs in cardiac regeneration and discusses the practical applications of hPSC-derived CMCs; furthermore, it outlines the relevance of directly reprogrammed CMCs in regenerative medicine.

Exosomes derived from bone marrow mesenchymal stromal cells promote remyelination and reduce neuroinflammation in the demyelinating central nervous system

Injury of oligodendrocytes (OLs) induces demyelination, and patients with neurodegenerative diseases exhibit demyelination concomitantly with neurological deficit and cognitive impairment. Oligodendrocyte progenitor cells (OPCs) are present in the adult central nervous system (CNS), and they can proliferate, differentiate, and remyelinate axons after damage. However, remyelination therapies are not in clinical use. Multiple sclerosis (MS) is a major demyelinating disease in the CNS. Mesenchymal stromal cells (MSCs) have demonstrated therapeutic promise in animal models and in clinical trials of MS. Exosomes are nanoparticles generated by nearly all cells and they mediate cell-cell communication by transferring cargo biomaterials. Here, we hypothesize that exosomes harvested from MSCs have a similar therapeutic effect on enhancement of remyelination as that of MSCs. In the present study we employed exosomes derived from rhesus monkey MSCs (MSC-Exo). Two mouse models of demyelination were employed: 1) experimental autoimmune encephalomyelitis (EAE), an animal model of MS; and 2) cuprizone (CPZ) diet model, a toxic demyelination model. MSC-Exo or PBS were intravenously injected twice a week for 4 weeks, starting on day 10 post immunization in EAE mice, or once a week for 2 weeks starting on the day of CPZ diet withdrawal. Neurological and cognitive function were tested, OPC differentiation and remyelination, neuroinflammation and the potential underlying mechanisms were investigated using immunofluorescent staining, transmission electron microscopy and Western blot. Data generated from the EAE model revealed that MSC-Exo cross the blood brain barrier (BBB) and target neural cells. Compared with the controls (p < 0.05), treatment with MSC-Exo: 1) significantly improved neurological outcome; 2) significantly increased the numbers of newly generated OLs (BrdU+/APC+) and mature OLs (APC+), and the level of myelin basic protein (MBP); 3) decreased amyloid-β precursor protein (APP)+ density; 4) decreased neuroinflammation by increasing the M2 phenotype and decreasing the M1 phenotype of microglia, as well as their related cytokines; 5) inhibited the TLR2/IRAK1/NFκB pathway. Furthermore, we confirmed that the MSC-Exo treatment significantly improved cognitive function, promoted remyelination, increased polarization of M2 phenotype and blocked TLR2 signaling in the CPZ model. Collectively, MSC-Exo treatment promotes remyelination by both directly acting on OPCs and indirectly by acting on microglia in the demyelinating CNS. This study provides the cellular and molecular basis for this cell-free exosome therapy on remyelination and modulation of neuroinflammation in the CNS, with great potential for treatment of demyelinating and neurodegenerative disorders.

Realistic Dilemma and Solution of Stem Cell Application Supervision in China

The regulatory system for the use of stem cells in China has experienced three stages of development. The internal reason for the constant changes is a lack of understanding of the legal nature of stem cells as a special object, and the external reason is the failure to reach a balance between encouraging and restricting the use of stem cells. With the introduction of China's first special regulations on stem cells in 2015, a dual-track application system for stem cell drugs and therapies has begun to take shape, but there still exists several problems such as gaps in the provisions of the upper law and unclear division of supervisory responsibilities. With respect to the regulatory system, a dual-track system with drug regulation as the mainstay and medical therapy as the supplement should be clarified. In terms of supervision design, stem cell medical therapy should be managed hierarchically according to the degree of risk, and a model should be formed in which the Ministry of Science and Technology conducts general supervision of the entire process, and the Health Commission and the Drug Administration conduct special supervision of clinical applications.

Modern Approaches to Acellular Therapy in Bone and Dental Regeneration

An approach called cell-free therapy has rapidly developed in regenerative medicine over the past decade. Understanding the molecular mechanisms and signaling pathways involved in the internal potential of tissue repair inspires the development of new strategies aimed at controlling and enhancing these processes during regeneration. The use of stem cell mobilization, or homing for regeneration based on endogenous healing mechanisms, prompted a new concept in regenerative medicine: endogenous regenerative medicine. The application of cell-free therapeutic agents leading to the recruitment/homing of endogenous stem cells has advantages in overcoming the limitations and risks associated with cell therapy. In this review, we discuss the potential of cell-free products such as the decellularized extracellular matrix, growth factors, extracellular vesicles and miRNAs in endogenous bone and dental regeneration.

The role of keratinocyte function on the defected diabetic wound healing

Non-healing wounds are a major complication of diabetes that can lead to limb amputation and disability in patients. The normal process of wound repair progresses through well-defined stages including hemostasis, inflammation, proliferative, and remodeling, which may be impaired in diabetic wounds. In recent years, it has been reported that keratinocytes, a major cell type in human skin, play a key role in the healing process of wounds. In this overview, firstly, a summary of the wound healing process is provided and the role of keratinocytes in wound healing is briefly reviewed. Then, a set of evidence about the impaired keratinocytes activities in diabetic wounds and clinical trials focused mainly on improving keratinocytes in the context of diabetic wound therapeutics are summarized. Keratinocytes can produce signaling molecules that act in a paracrine and autocrine way, causing pleiotropic effects on various cell types. The affected cells respond to keratinocytes by creating several signaling molecules, which also adjust keratinocyte activation through wound healing. In diabetic wounds, disruption of various biological mechanisms leads to dysfunction of keratinocytes including impaired migration, adhesion, and proliferation. The function of abnormal keratinocytes can lead to poor diabetic wound healing. Taken together, clarification of molecular and functional disturbances of keratinocyte cells and applying them in diabetic wounds can contribute to enhanced treatment of diabetic wounds. Based on the location of keratinocytes in the epidermis and the central role of keratinocytes in the diabetic wound healing process, applying keratinocytes has great potential for the treatment of diabetic burn wounds.

Bone Scaffolds: An Incorporation of Biomaterials, Cells, and Biofactors

Large injuries to bones are still one of the most challenging musculoskeletal problems. Tissue engineering can combine stem cells, scaffold biomaterials, and biofactors to aid in resolving this complication. Therefore, this review aims to provide information on the recent advances made to utilize the potential of biomaterials for making bone scaffolds and the assisted stem cell therapy and use of biofactors for bone tissue engineering. The requirements and different types of biomaterials used for making scaffolds are reviewed. Furthermore, the importance of stem cells and biofactors (growth factors and extracellular vesicles) in bone regeneration and their use in bone scaffolds and the key findings are discussed. Lastly, some of the main obstacles in bone tissue engineering and future trends are highlighted.

Understanding cell culture dynamics: a tool for defining protocol parameters for improved processes and efficient manufacturing using human embryonic stem cells

Standardization is crucial when culturing cells including human embryonic stem cells (hESCs) which are valuable for therapy development and disease modeling. Inherent issues regarding reproducibility of protocols are problematic as they hinder translation to good manufacturing practice (GMP), thus reducing clinical efficacy and uptake. Pluripotent cultures require standardization to ensure that input material is consistent prior to differentiation, as inconsistency of input cells creates end-product variation. To improve protocols, developers first must understand the cells they are working with and their related culture dynamics. This innovative work highlights key conditions required for optimized and cost-effective bioprocesses compared to generic protocols typically implemented. This entailed investigating conditions affecting growth, metabolism, and phenotype dynamics to ensure cell quality is appropriate for use. Results revealed critical process parameters (CPPs) including feeding regime and seeding density impact critical quality attributes (CQAs) including specific metabolic rate (SMR) and specific growth rate (SGR). This implied that process understanding, and control is essential to maintain key cell characteristics, reduce process variation and retain CQAs. Examination of cell dynamics and CPPs permitted the formation of a defined protocol for culturing H9 hESCs. The authors recommend that H9 seeding densities of 20,000 cells/cm2, four-day cultures or three-day cultures following a recovery passage from cryopreservation and 100% medium exchange after 48 hours are optimal. These parameters gave ~SGR of 0.018 hour-1 ± 1.5x10-3 over three days and cell viabilities ≥95%±0.4, while producing cells which highly expressed pluripotent and proliferation markers, Oct3/4 (>99% positive) and Ki-67 (>99% positive).

Tendon Tissue Repair in Prospective of Drug Delivery, Regenerative Medicines, and Innovative Bioscaffolds

The natural healing capacity of the tendon tissue is limited due to the hypovascular and cellular nature of this tissue. So far, several conventional approaches have been tested for tendon repair to accelerate the healing process, but all these approaches have their own advantages and limitations. Regenerative medicine and tissue engineering are interdisciplinary fields that aspire to develop novel medical devices, innovative bioscaffold, and nanomedicine, by combining different cell sources, biodegradable materials, immune modulators, and nanoparticles for tendon tissue repair. Different studies supported the idea that bioscaffolds can provide an alternative for tendon augmentation with an enormous therapeutic potentiality. However, available data are lacking to allow definitive conclusion on the use of bioscaffolds for tendon regeneration and repairing. In this review, we provide an overview of the current basic understanding and material science in the field of bioscaffolds, nanomedicine, and tissue engineering for tendon repair.

Bone marrow mesenchymal stem cell derived exosomal miR-455-5p protects against spinal cord ischemia reperfusion injury

At present, much more studies have focused on the therapeutic effect of exosome-delivered microRNAs on diseases. Previous study has shown that miR-455-5p is downregulated in ischemic stroke, but little is known about the role of exosome-delivered miR-455-5p in spinal cord ischemia reperfusion (SCIR) injury. Herein, we isolated exosomes from bone marrow mesenchymal stem cells (BMSCs) transfected with lentivirus vectors containing miR-455-5p. SCIR rat model was established after the intrathecal injection of exosomes containing miR-455-5p. The expression level of miR-455-5p was downregulated after SCIR, administration of exosomal miR-455-5p enhanced the level of miR-455-5p in the injured spinal cord. Hind-limb motor function scores indicated that exosomal miR-455-5p improved the recovery of hind-limb function of SCIR rats. HE staining and Nissl staining showed that miR-455-5p enriched exosomes reduced histopathological abnormalities after SCIR. Double immunofluorescence staining revealed that exosomes containing miR-455-5p reduced apoptosis of neurons, and activated autophagy in neurons after SCIR. We observed that the expression of Nogo-A, a direct target of miR-455-5p, was decreased in the spinal cord of exosomal miR-455-5p administrated SCIR rats. Targeting relationship between miR-455-5p and Nogo-A was verified by dual-luciferase reporter assay. In summary, exosomes containing miR-455-5p had the neuroprotective effects on SCIR injury by promoting autophagy and inhibiting apoptosis of neurons.

Immunomodulatory Actions of Mesenchymal Stromal Cells (MSCs) in Osteoarthritis of the Knee

Cellular therapy offers regeneration which curbs osteoarthritis of the knee. Among cellular therapies, mesenchymal stromal cells (MSCs) are readily isolated from various sources as culture expanded and unexpanded cellular population which are used as therapeutic products. Though MSCs possess a unique immunological and regulatory profile through cross-talk between MSCs and immunoregulatory cells (T cells, NK cells, dendritic cells, B cells, neutrophils, monocytes, and macrophages), they provide an immunotolerant environment when transplanted to the site of action. Immunophenotypic profile allows MSCs to escape immune surveillance and promotes their hypoimmunogenic or immune-privileged status. MSCs do not elicit a proliferative response when co-cultured with allogeneic T cells in vitro. MSCs secrete a wide range of anti-inflammatory mediators such as PGE-2, IDO, IL-1Ra, and IL-10. They also stimulate the resilient chondrogenic progenitors and enhance the chondrocyte differentiation by secretion of BMPs and TGFβ1. We highlight the various mechanisms of MSCs during tissue healing signals, their interaction with the immune system, and the impact of their lifespan in the management of osteoarthritis of the knee. A better understanding of the immunobiology of MSC renders them as an efficient therapeutic product for the management of osteoarthritis of the knee.

Exosome-loaded hydrogels: a new cell-free therapeutic approach for skin regeneration

The treatment of unhealable and chronic cutaneous wounds is a significant challenge for the healthcare system. Hence, there has been heightened interest in the development of innovative therapeutic approaches for the acceleration of wound healing. Regenerative medicine based on mesenchymal stem cells (MSCs) has shown appropriate potential in skin repair. The regenerative properties of stem cells are mainly attributed to paracrine effects of secreted products, including exosomes. There are advantages to using exosomes as a cell-free approach instead of direct application of stem cells. Exosomes have nanoscale dimension and are immune-tolerant, Exosomes have the nanoscale dimension and are immune-tolerant. They can easily endocytose, and transfer the cargo content to recipient cells. They contribute to the regulation of the wound healing process by activating specific signaling pathways. To preserve exosome bioactivity and controlled release of effective concentration during prolonged wound care, the design of an optimized delivery system is necessary. Accordingly, hydrogels with their unique properties are promising candidates as exosome delivery and wound management products. This article investigates the characteristics of exosomes, their molecular mechanism in wound healing, and the advantages of the hydrogel delivery system. Also, published reports on the potential of exosome-loaded hydrogels in skin regeneration have been reviewed.

Human Umbilical Cord Mesenchymal Stem Cell-Derived Exosomes Attenuate Oxygen-Glucose Deprivation/Reperfusion-Induced Microglial Pyroptosis by Promoting FOXO3a-Dependent Mitophagy

Background

Mesenchymal stem cell-derived exosomes (MSC-exos) have been recognized as a promising therapeutic strategy for neonatal hypoxic-ischemic brain damage (HIBD). Recently, microglial pyroptosis was shown to play a vital role in the progression of neonatal HIBD. However, whether MSC-exos improve HIBD by regulating microglial pyroptosis remains unknown.

Methods

Exosomes were isolated from human umbilical cord mesenchymal stem cells (huMSCs) and identified by transmission electron microscopy (TEM), western blot, and nanoparticle tracking analysis (NTA). BV-2 cells were subjected to oxygen-glucose deprivation/reoxygenation (OGD/R) to induce microglial ischemia/reperfusion (I/R) in vitro. CCK-8, ELISA, western blot, and Hoechst 33342/PI double staining were performed to detect the pyroptosis of BV-2 cells. Conditioned medium (CM) from BV-2 cells exposed to different treatments was used to investigate its effect on neuronal injury. Moreover, 3-methyladenine (3-MA) and mitochondrial division inhibitor-1 (mdi-1) were used to verify the involvement of mitophagy in the protection of MSC-exos against OGD/R-induced pyroptosis in BV-2 cells. Finally, FOXO3a siRNA was used to investigate the involvement of FOXO3a in MSC-exo-induced mitophagy and pyroptosis inhibition.

Results

Exosomes from huMSCs were successfully extracted. In OGD/R-exposed BV-2 cells, MSC-exos increased cell viability and decreased the expression of NLRP3, cleaved caspase-1, and GSDMD-N as well as the release of IL-1β and IL-18. Compared with CM from OGD/R-exposed BV-2 cells treated with PBS, CM from OGD/R-exposed BV-2 cells treated with MSC-exos significantly increased the viability of SH-SY5Y cells and decreased LDH release. MSC-exos also increased the expression of TOM20 and COX IV in OGD/R-exposed BV-2 cells. Additionally, 3-MA and mdi-1 attenuated the inhibition of pyroptosis with MSC-exo treatment. Furthermore, FOXO3a siRNA partially abolished the neuroprotective effect of MSC-exos and attenuated mitophagy and pyroptosis inhibition induced by MSC-exo treatment.

Conclusions

Our findings demonstrated that MSC-exos increased FOXO3a expression to enhance mitophagy, therefore protecting microglia from I/R-induced pyroptosis and alleviating subsequent neuronal injury.

Advances in mesenchymal stem cell conditioned medium-mediated periodontal tissue regeneration

Periodontitis is a chronic inflammatory disease that leads to the destruction of both soft and hard periodontal tissues. Complete periodontal regeneration in clinics using the currently available treatment approaches is still a challenge. Mesenchymal stem cells (MSCs) have shown promising potential to regenerate periodontal tissue in various preclinical and clinical studies. The poor survival rate of MSCs during in vivo transplantation and host immunogenic reaction towards MSCs are the main drawbacks of direct use of MSCs in periodontal tissue regeneration. Autologous MSCs have limited sources and possess patient morbidity during harvesting. Direct use of allogenic MSCs could induce host immune reaction. Therefore, the MSC-based indirect treatment approach could be beneficial for periodontal regeneration in clinics. MSC culture conditioned medium (CM) contains secretomes that had shown immunomodulatory and tissue regenerative potential in pre-clinical and clinical studies. MSC-CM contains a cocktail of growth factors, cytokines, chemokines, enzymes, and exosomes, extracellular vesicles, etc. MSC-CM-based indirect treatment has the potential to eliminate the drawbacks of direct use of MSCs for periodontal tissue regeneration. MSC-CM holds the tremendous potential of bench-to-bed translation in periodontal regeneration applications. This review focuses on the accumulating evidence indicating the therapeutic potential of the MSC-CM in periodontal regeneration-related pre-clinical and clinical studies. Recent advances on MSC-CM-based periodontal regeneration, existing challenges, and prospects are well summarized as guidance to improve the effectiveness of MSC-CM on periodontal regeneration in clinics.

The Clinical Trials of Mesenchymal Stromal Cells Therapy

Mesenchymal stromal cells (MSCs) are a heterogeneous population of adult stem cells, which are multipotent and possess the ability to differentiate/transdifferentiate into mesodermal and nonmesodermal cell lineages. MSCs display broad immunomodulatory properties since they are capable of secreting growth factors and chemotactic cytokines. Safety, accessibility, and isolation from patients without ethical concern make MSCs valuable sources for cell therapy approaches in autoimmune, inflammatory, and degenerative diseases. Many studies have been conducted on the application of MSCs as a new therapy, but it seems that a low percentage of them is related to clinical trials, especially completed clinical trials. Considering the importance of clinical trials to develop this type of therapy as a new treatment, the current paper is aimed at describing characteristics of MSCs and reviewing relevant clinical studies registered on the NIH database during 2016-2020 to discuss recent advances on MSC-based therapeutic approaches being used in different diseases.

Advances in Tissue Engineering and Implications for Oral and Maxillofacial Reconstruction

BACKGROUND

Reconstructive surgery in the oral and maxillofacial region poses many challenges due to the complexity of the facial skeleton and the presence of composite defects involving soft tissue, bone and nerve defects.

METHODS

Current methods of reconstruction include autologous grafting techniques with local or regional rotational flaps or microvascular free flaps, allografts, xenografts and prosthetic devices.

RESULTS

Tissue engineering therapies utilizing stem cells provide promise for enhancing the current reconstructive options.

CONCLUSIONS

This article is a review on tissue engineering strategies applicable to specialists who treat oral and maxillofacial defects.

PRACTICAL IMPLICATIONS

We review advancements in hard tissue regeneration for dental rehabilitation, soft tissue engineering, nerve regeneration and innovative strategies for reconstruction of major defects.

A contemporary review of therapeutic and regenerative management of intracerebral hemorrhage

Intracerebral hemorrhage (ICH) remains a common and debilitating form of stroke. This neurological emergency must be diagnosed and treated rapidly yet effectively. In this article, we review the medical, surgical, repair, and regenerative treatment options for managing ICH. Topics of focus include the management of blood pressure, intracranial pressure, coagulopathy, and intraventricular hemorrhage, as well as the role of surgery, regeneration, rehabilitation, and secondary prevention. Results of various phase II and III trials are incorporated. In summary, ICH patients should undergo rapid evaluation with neuroimaging, and early interventions should include systolic blood pressure control in the range of 140 mmHg, correction of coagulopathy if indicated, and assessment for surgical intervention. ICH patients should be managed in dedicated neurosurgical intensive care or stroke units where continuous monitoring of neurological status and evaluation for neurological deterioration is rapidly possible. Extravasation of hematoma may be helpful in patients with intraventricular extension of ICH. The goal of care is to reduce mortality and enable multimodal rehabilitative therapy.

Engineered neural tissue made using clinical-grade human neural stem cells supports regeneration in a long gap peripheral nerve injury model

A surgical autograft remains the clinical gold-standard therapy for gap repair following peripheral nerve injury, however, challenges remain with achieving full recovery and reducing donor-site morbidity. Engineered Neural Tissue (EngNT) manufactured using differentiated CTX0E03 human stem cells (EngNT-CTX) has been developed as a potential 'off the shelf' allogeneic autograft replacement. Ensheathed within a collagen membrane developed to facilitate biomechanical integration, EngNT-CTX was used to bridge a critical-length (15 mm) sciatic nerve gap injury in athymic nude rats. The effectiveness of EngNT-CTX was compared to an autograft using outcome measures that assessed neuronal regeneration and functional recovery at 8 and 16 weeks. At both time points EngNT-CTX restored electrophysiological nerve conduction and functional reinnervation of downstream muscles to the same extent as the autograft. Histological analysis confirmed that more motor neurons had successfully regenerated through the repair in EngNT-CTX in comparison to the autograft at 8 weeks, which was consistent with the electrophysiology, with the number of motor neurons similar in both groups by 16 weeks. The total number of neurons (motor + sensory) was greater in autografts than EngNT-CTX at 8 weeks, indicating that more sensory fibres may have sprouted in those animals at this time point. In conclusion, this study provides evidence to support the effectiveness of EngNT-CTX as a replacement for the nerve autograft, as the functional regeneration assessed through histological and electrophysiological outcome measures demonstrated equivalent performance. STATEMENT OF SIGNIFICANCE: Following injury a peripheral nerve has the capacity to regenerate naturally, however, in the case of severe damage where there is a gap the current gold-standard microsurgical intervention is an autograft. This is associated with serious limitations including tissue availability and donor-site morbidity. Tissue engineering aims to overcome these limitations by building a construct from therapeutic cells and biomaterials as a means to mimic and replace the autograft. In this study engineered neural tissue (EngNT) was manufactured using human stem cells (CTX) to bridge a critical-length gap injury. When compared to the autograft in an animal model the EngNT-CTX construct restored function to an equivalent or greater extent.

Human hepatocyte-derived extracellular vesicles attenuate the carbon tetrachloride-induced acute liver injury in mice

Acute liver injury (ALI) induced by chemicals or viruses can progress rapidly to acute liver failure (ALF), often resulting in death of patients without liver transplantation. Since liver transplantation is limited due to a paucity of donors, expensive surgical costs, and severe immune rejection, novel therapies are required to treat liver injury. Extracellular vesicles (EVs) are used for cellular communication, carrying RNAs, proteins, and lipids and delivering them intercellularly after being endocytosed by target cells. Recently, it was reported that EVs secreted from human hepatocytes have an ability to modulate the immune responses; however, these roles of EVs secreted from human hepatocytes were studied only with in vitro experiments. In the present study, we evidenced that EVs secreted from human hepatocytes attenuated the CCL₄-induced ALI by inhibiting the recruitment of monocytes through downregulation of chemokine receptor in the bone marrow and recruitment of neutrophils through the reduction of C-X-C motif chemokine ligand 1 (CXCL1) and CXCL2 expression levels in the liver.

Development of a Bone-Mimetic 3D Printed Ti6Al4V Scaffold to Enhance Osteoblast-Derived Extracellular Vesicles' Therapeutic Efficacy for Bone Regeneration

Extracellular Vesicles (EVs) are considered promising nanoscale therapeutics for bone regeneration. To date, EVs are typically procured from cells on 2D tissue culture plastic, an artificial environment that limits cell growth and does not replicate in situ biochemical or biophysical conditions. This study investigated the potential of 3D printed titanium scaffolds coated with hydroxyapatite to promote the therapeutic efficacy of osteoblast-derived EVs. Ti6Al4V titanium scaffolds with different pore sizes (500 and 1000 µm) and shapes (square and triangle) were fabricated by selective laser melting. A bone-mimetic nano-needle hydroxyapatite (nnHA) coating was then applied. EVs were procured from scaffold-cultured osteoblasts over 2 weeks and vesicle concentration was determined using the CD63 ELISA. Osteogenic differentiation of human bone marrow stromal cells (hBMSCs) following treatment with primed EVs was evaluated by assessing alkaline phosphatase activity, collagen production and calcium deposition. Triangle pore scaffolds significantly increased osteoblast mineralisation (1.5-fold) when compared to square architectures (P ≤ 0.001). Interestingly, EV yield was also significantly enhanced on these higher permeability structures (P ≤ 0.001), in particular (2.2-fold) for the larger pore structures (1000 µm). Furthermore osteoblast-derived EVs isolated from triangular pore scaffolds significantly increased hBMSCs mineralisation when compared to EVs acquired from square pore scaffolds (1.7-fold) and 2D culture (2.2-fold) (P ≤ 0.001). Coating with nnHA significantly improved osteoblast mineralisation (>2.6-fold) and EV production (4.5-fold) when compared to uncoated scaffolds (P ≤ 0.001). Together, these findings demonstrate the potential of harnessing bone-mimetic culture platforms to enhance the production of pro-regenerative EVs as an acellular tool for bone repair.

Microneedle arrays integrated with living organisms for smart biomedical applications

Various living organisms have proven to influence human health significantly, either in a commensal or pathogenic manner. Harnessing the creatures may remarkably improve human healthcare and cure the intractable illness that is challenged using traditional drugs or surgical approaches. However, issues including limited biocompatibility, poor biosafety, inconvenience for personal handling, and low patient compliance greatly hinder the biomedical and clinical applications of living organisms when adopting them for disease treatment. Microneedle arrays (MNAs), emerging as a promising candidate of biomedical devices with the functional diversity and minimal invasion, have exhibited great potential in the treatment of a broad spectrum of diseases, which is expected to improve organism-based therapies. In this review, we systemically summarize the technologies employed for the integration of MNAs with specific living organisms including diverse viruses, bacteria, mammal cells and so on. Moreover, their applications such as vaccination, anti-infection, tumor therapy and tissue repairing are well illustrated. Challenges faced by current strategies, and the perspectives of integrating more living organisms, adopting smarter materials, and developing more advanced technologies in MNAs for future personalized and point-of-care medicine, are also discussed. It is believed that the combination of living organisms with functional MNAs would hold great promise in the near future due to the advantages of both biological and artificial species.

Human ESC-derived Neuromesodermal Progenitors (NMPs) Successfully Differentiate into Mesenchymal Stem Cells (MSCs)

Mesenchymal Stem Cells (MSCs), as an adult stem cell type, are used to treat various disorders in clinics. However, derivation of homogenous and adequate amount of MSCs limits the regenerative treatment potential. Although mesoderm is the main source of mesenchymal progenitors during embryonic development, neuromesodermal progenitors (NMPs), reside in the primitive streak during development, is known to differentiate into paraxial mesoderm. In the current study, we generated NMPs from human embryonic stem cells (hESC), subsequently derived MSCs and characterized this cell population in vitro and in vivo. Using a bFGF and CHIR induced NMP formation protocol followed by serum containing culture conditions; here we show that MSCs can be generated from NMPs identified by not only the expression of T/Bra and Sox 2 but also FLK-1/PDGFRα in our study. NMP-derived MSCs were plastic adherent fibroblast like cells with colony forming capacity and trilineage (osteo-, chondro- and adipo-genic) differentiation potential. In the present study, we demonstrate that NMP-derived MSCs have an endothelial tendency which might be related to their FLK-1+/PDGFRα + NMP origin. NMP-derived MSCs displayed a protein expression profile of characterized MSCs. Growth factor and angiogenesis related pathway proteins were similarly expressed in NMP-derived MSCs and characterized MSCs. NMP-derived MSCs keep characteristics after short-term and long-term freeze-thaw cycles and localized into bone marrow followed by tail vein injection into NOD/SCID mice. Together, these data showed that hESC-derived NMPs might be used as a precursor cell population for MSC derivation and could be used for in vitro and in vivo research.

Update of the recommendations of the Sociedade Portuguesa de Cuidados Intensivos and the Infection and Sepsis Group for the approach to COVID-19 in Intensive Care Medicine

INTRODUCTION

The Sociedade Portuguesa de Cuidados Intensivos and the Infection and Sepsis Group have previously issued health service and management recommendations for critically ill patients with COVID-19. Due to the evolution of knowledge, the panel of experts was again convened to review the current evidence and issue updated recommendations.

METHODS

A national panel of experts who declared that they had no conflicts of interest regarding the development of the recommendations was assembled. Operational questions were developed based on the PICO methodology, and a rapid systematic review was conducted by consulting different bibliographic sources. The panel determined the direction and strength of the recommendations using two Delphi rounds, conducted in accordance with the principles of the GRADE system. A strong recommendation received the wording "is recommended", and a weak recommendation was written as "is suggested."

RESULTS

A total of 48 recommendations and 30 suggestions were issued, covering the following topics: diagnosis of SARS-CoV-2 infection, coinfection and superinfection; criteria for admission, cure and suspension of isolation; organization of services; personal protective equipment; and respiratory support and other specific therapies (antivirals, immunomodulators and anticoagulation).

CONCLUSION

These recommendations, specifically oriented to the Portuguese reality but that may also apply to Portuguese-speaking African countries and East Timor, aim to support health professionals in the management of critically ill patients with COVID-19. They will be continuously reviewed to reflect the progress of our understanding and the treatment of this pathology.

Future generation of combined multimodal approach to treat brain glioblastoma multiforme and potential impact on micturition control

Glioblastoma remains lethal even when treated with standard therapy. This review aims to outline the recent development of various advanced therapeutics for glioblastoma and briefly discuss the potential impact of glioblastoma and some of its therapeutic approaches on the neurological function micturition control. Although immunotherapy led to success in treating hematological malignancies, but no similar success occurred in treatment for brain glioblastoma. Neither regenerative medicine nor stem cell therapy led to astounding success in glioblastoma. However, CRISPR Cas system holds potential in multiple applications due to its capacity to knock-in and knock-out genes, modify immune cells and cell receptors, which will enable it to address clinical challenges in immunotherapy such as CAR-T and regenerative therapy for brain glioblastoma, improving the precision and safety of these approaches. The studies mentioned in this review could indicate that glioblastoma is a malignant disease with multiple sophisticated barriers to be overcome and more challenges might arise in the attempt of researchers to yield a successful cure. A multimodal approach of future generation of refined and safe therapeutics derived from CRISPR Cas therapeutics, immunotherapy, and regenerative therapeutics mentioned in this review might prolong survival or even contribute towards a potential cure for glioblastoma.

Rebuilding the hematopoietic stem cell niche: Recent developments and future prospects

Hematopoietic stem cells (HSCs) have proven their clinical relevance in stem cell transplantation to cure patients with hematological disorders. Key to their regenerative potential is their natural microenvironment - their niche - in the bone marrow (BM). Developments in the field of biomaterials enable the recreation of such environments with increasing preciseness in the laboratory. Such artificial niches help to gain a fundamental understanding of the biophysical and biochemical processes underlying the interaction of HSCs with the materials in their environment and the disturbance of this interplay during diseases affecting the BM. Artificial niches also have the potential to multiply HSCs in vitro, to enable the targeted differentiation of HSCs into mature blood cells or to serve as drug-testing platforms. In this review, we will introduce the importance of artificial niches followed by the biology and biophysics of the natural archetype. We will outline how 2D biomaterials can be used to dissect the complexity of the natural niche into individual parameters for fundamental research and how 3D systems evolved from them. We will present commonly used biomaterials for HSC research and their applications. Finally, we will highlight two areas in the field of HSC research, which just started to unlock the possibilities provided by novel biomaterials, in vitro blood production and studying the pathophysiology of the niche in vitro. With these contents, the review aims to give a broad overview of the different biomaterials applied for HSC research and to discuss their potentials, challenges and future directions in the field. STATEMENT OF SIGNIFICANCE: Hematopoietic stem cells (HSCs) are multipotent cells responsible for maintaining the turnover of all blood cells. They are routinely applied to treat patients with hematological diseases. This high clinical relevance explains the necessity of multiplication or differentiation of HSCs in the laboratory, which is hampered by the missing natural microenvironment - the so called niche. Biomaterials offer the possibility to mimic the niche and thus overcome this hurdle. The review introduces the HSC niche in the bone marrow and discusses the utility of biomaterials in creating artificial niches. It outlines how 2D systems evolved into sophisticated 3D platforms, which opened the gateway to applications such as, expansion of clinically relevant HSCs, in vitro blood production, studying niche pathologies and drug testing.

Assessment of Long-Term in vitro Multiplied Human Wharton's Jelly-Derived Mesenchymal Stem Cells prior to Their Use in Clinical Administration

The quantity of mesenchymal stem/stromal cells (MSCs) required for a particular therapy demands their subsequent expansion through ex vivo culture. During in vitro multiplication, they undergo replicative senescence which may alter their genetic stability. Therefore, this study was aimed to analyze cellular, molecular, and chromosomal alterations in Wharton's jelly-derived MSCs (WJ-MSCs) during their in vitro sequential passages, where WJ-MSCs were sequentially passaged up to P14 and cells were evaluated at an interval of P2, P6, P10, and P14. They were examined for their morphology, tumorigenicity, surface markers, stemness markers, DNA damage, chromosomal aberration, and telomere length. We have processed five full-term delivered human umbilical cord samples to obtain WJ-MSCs. Morphological appearance observed at initial stages was small fine spindle-shaped WJ-MSCs which were transformed to flat, long, and broader cells in later passages. The cell proliferation rate was gradually decreased after the 10th passage. WJ-MSCs have expressed stemness markers OCT-4 and NANOG, while they showed high expression of positive surface markers CD90 and CD105 and lower expression of CD34 and CD45. They were non-tumorigenic with slow cellular aging during subsequent passages. There was no chromosomal abnormality up to the 14th passage, while increase in comet score and decrease in telomere length were observed in later passages. Hence, our study suggests that early and middle passaged (less than P10) WJ-MSCs are good candidates for clinical administration for treatment.