Current Stem Cell Research & Therapy - Volume 18, Issue 4, 2023

Smoking habits represent a cardiovascular risk factor with a tremendous impact on health. Other than damaging differentiated and functional cells of the cardiovascular system, they also negatively affect reparative mechanisms, such as those involved in cardiac fibrosis and in endothelial progenitor cell (EPC) activation. In recent years, alternative smoking devices, dubbed modified tobacco risk products (MRPs), have been introduced, but their precise impact on human health is still under evaluation. Also, they have not been characterized yet about the possible negative effects on cardiovascular reparative and regenerative cells, such as EPCs or pluripotent stem cells. In this perspective, we critically review the still scarce available data on the effects of MRPs on molecular and cellular mechanisms of cardiovascular repair and regeneration.

Cancer stem cells (CSCs) are correlated with poor clinical outcomes due to their contribution to chemotherapy resistance and the formation of metastasis. Multiple cell surface and enzymatic markers have been characterized to identify CSCs, which is important for diagnosis, therapy, and prognosis. This review underlines the role of CSCs and circulating tumor cells (CTCs) in tumor relapse and metastasis, the characteristics of CSC and CTC biomarkers, and the techniques used to detect these cells. We also summarized novel therapeutic approaches toward targeting CSCs, especially focusing on the role of immune checkpoint blockades (ICB), such as anti-programmed death 1 (anti-PD1) and antiprogrammed death ligand-1 (anti-PDL1) therapies. Additionally, we address an intriguing new mechanism of action for small molecular drugs, such as telomere-targeted therapy 6-thio-2’deoxyguanosine (6- thio-dG), and how it reshapes tumor microenvironment to overcome ICB resistance. There are indications, that personalized cancer therapy targeting CSC populations in conjunction with immune-mediated strategy hold promise for the removal of residual therapy-resistant CSCs in the near future.

Bones normally function to provide both mechanical and locomotion supports in the body. They are highly specialized connective tissues that are characterized by mineralized extracellular components, which provide both rigidity and strength to bones. Stem cells hold great potentials for both the repair and regeneration of different tissue types, including bone tissues. The future use of stem cell therapy is promising for developing regenerative medicine approaches to treat disorders and diseases in a wide range of tissues such as cartilages and bones. Data have been accumulated recently on the application of different stem cell types in bone repair, regeneration, and disorders. In this article, we briefly describe the bone structure and review research progress and recently accumulated data on stem cell differentiation into osteoblasts as well as discuss the contributions of stem cell types to bone and cartilage repair, regeneration, and disease.

Bone tissue engineering (BTE) is based on the participation and combination of different biomaterials, cells, and bioactive molecules to generate biosynthetic grafts for bone regeneration. Electrospinning has been used to fabricate fibrous scaffolds, which provide nanoscale architecture comprising interconnecting pores, resembling the natural hierarchy of tissues and enabling the formation of artificial functional tissues. Electrospun fibers for BTE applications have been mostly produced from polymers (chitosan, alginate, polycaprolactone, polylactic acid) and bioceramics (hydroxyapatite). Stem cells are among the most prolific cell types employed in regenerative medicine owing to their self-renewal and differentiation capacity. Most importantly, bioactive molecules, such as synthetic drugs, growth factors, and phytocompounds, are consistently used to regulate cell behavior inducing differentiation towards the osteoblast lineage. An expanding body of literature has provided evidence that these electrospun fibers loaded with bioactive molecules support the differentiation of stem cells towards osteoblasts. Thus, this review briefly describes the current development of polymers and bioceramic-based electrospun fibers and the influence of bioactive molecules in these electrospun fibers on bone tissue regeneration.

Spinal cord injury (SCI) is a catastrophic event that incurs substantial personal and social costs. The complex pathophysiology associated with SCI often limits the regeneration of nerve tissue at the injured site and leads to permanent nerve damage. With advances in stem cell biology, the field of regenerative medicine offers the hope of solving this challenging problem. Neural stem/progenitor cells (NSPCs) possess nerve regenerative and neuroprotective effects, and transplanting NSPCs in their optimized form into an injured area holds promising therapeutic potential for SCI. In this review, we summarize the advantages and disadvantages of NSPCs derived from different sources while highlighting the utility of NSPCs derived from induced pluripotent stem cells, an NSPC source with superior advantages, according to data from in vivo animal models and the latest clinical trials.

Background: Intestinal disease is a common disease, which can cause serious digestion and absorption disorders, endanger the lives of patients and seriously affect the quality of life of people. Finding an effective treatment is a difficult problem at present, and stem cell therapy as a treatment has high application potential in intestinal-related diseases. Purpose: This paper mainly summarizes the mechanism, research progress and future development trend of stem cells in the treatment of intestinal diseases in the past decade, hoping to provide a reference for future researchers in the research and application of stem cells and intestinal diseases. Methods: Stem cells, inflammatory bowel diseases, Crohn's disease, radiation-induced intestinal injury, radiation enterocolitis, and extracellular vesicles were used as search terms. Relevant references in the past ten years were searched in CNKI journal full-text database, PubMed database, VIP network and Wanfang medical network, and 80 literature studies meeting the requirements were finally included for review. Results: This paper summarizes the research and application of stem cells in intestinal diseases from 2012 to 2021, and expounds on the specific mechanism of stem cells in the treatment of intestinal diseases. It has been found that stem cells can treat intestinal injury or inflammation in different ways. Conclusion: Future stem cells may also be used to reverse the natural aging of intestinal function, improve intestinal function, and strengthen gastrointestinal function.

Introduction: Bone metabolism has an essential role in bone disease, but its specific mechanism remains unclear. Y-Box Binding Protein 1 (YBX1) is a gene with broad nucleic acid binding properties, which encodes a highly conserved cold shock domain protein. Previous studies have shown that YBX1 is closely related to cell differentiation. However, the function of YBX1 in osteoblast differentiation of bone marrow mesenchymal stem cells (MSCs) was unclear. Methods: To explore the effect and specific mechanism of YBX1 in osteogenic differentiation of MSCs, we used PCR, Western blot, Alizarin red Staining, alkaline phosphatase (ALP) assays, and siRNA knockdown in our research. We found that YBX1 gradually increased during the process of osteogenic differentiation of MSCs. YBX1 siRNA could negatively regulate the MSCs osteogenic differentiation. Mechanistic studies revealed that YBX1 knockdown could inhibit PI3K/AKT pathway. Furthermore, the specific agonist (SC79) of PI3K/AKT pathway could restore the impaired MSCs osteogenic differentiation which was mediated by YBX1 knockdown. Taken together, we concluded that YBX1 could positively regulate the osteogenic differentiation of MSCs by activating the PI3K/AKT pathway. Results and Discussion: These results helped us further understand the mechanism of osteogenesis and revealed that YBX1 might be a selectable target in the bone repair field. Conclusion: Our study provides a new target and theoretical basis for the treatment of bone diseases.

Introduction: Articular cartilage is an avascular, aneural, and lymphatic tissue with limited capacity to regenerate. Numerous techniques have been employed to repair or regenerate; however, the success rate varies. In fact, most of them result in the formation of fibrocartilage, not hyaline cartilage. The future of treating cartilage defects lies in providing biological solutions through cartilage regeneration. Mesenchymal stem cells (MSCs) represent a promising therapy for cartilage regeneration. These cells secrete factors that enhance cartilage repair. This study studied the effects of intra-articular injection of human umbilical cord MSC (hUC-MSC) secretome on cartilage damage in a sheep model. Methods: Standardized rectangular (5x5 mm) full-thickness chondral defects were created in the lateral femoral condyle of 15 adult sheep and debrided down to the subchondral bone plate. Three treatment groups were tested: 4 microfracture perforations using 1.0mm diameter awls (group 1), intra-articular injection of hUC-MSC secretome (group 2), and a combination of microfracture and intra-articular injection of hUC-MSC secretome (group 3). The osteochondral repair was assessed at 6 months using an established macroscopic and histological analyses. Results: Macroscopically, combined therapy application shows significant cartilage repair improvement compared to microfracture alone (p=0.004). Microscopically, the application of combined therapy shows significant improvement of cartilage repair compared to secretome injection alone (p=0.031). Conclusion: Microfracture combined with injection of hUCB-MSCs secretome could be an effective alternative for repairing articular cartilage defects in vivo.

Background: Though adipose-derived stem cells (ADSCs) have potential applications for the repair and regeneration of damaged tissues, limited studies have defined the function of ADSCs on dermal fibroblasts. Our RNA-seq sequencing identified differentially expressed SOCS3 in frostbite injury. Objective: In the current study, we aim to examine the hypothesis that extracellular vesicles derived from adipose-derived mesenchymal stem cells (ADSCs-EVs) may modulate SOCS3/TGF-β1 signaling in wound healing of frostbite injury. Methods: sh-SOCS3 and sh-TGF-β1 were introduced to explore the biological role of SOCS3 in frostbite injury by detecting the proliferation and migration of human skin fibroblast (HSF) cells and the wound healing in mice. Furthermore, the extracted ADSCs-EVs were interfered with HSF cells in vitro or injected into the frostbitten mouse model in vivo. Results: Upregulation of SOCS3 occurred in the skin tissues of frostbitten mice. Compared to sh-NC, the wound healing rate of sh-SOCS3 presented higher on day 7(31.34±4.35 vs 41.83±3.74, p < 0.05) and day 14 (63.42±6.01 vs 88.99±5.12, p < 0.05) after injury. Silencing SOCS3 can promote frostbite wound healing. Moreover, SOCS3 downregulated TGF-β1 to suppress the proliferation and migration of HSF cells, thus impeding the skin wound healing. Additionally, ADSCs-EVs could enhance the proliferation and migration of HSF cells according to the results of CCK-8 assay (p < 0.05), scratch test (17.82±4.25 vs 49.78±2.54, p < 0.05) and Transwell assay (42.33±6.81 vs 91.33±7.02, p < 0.05), and regulate the expression of SOCS3/TGF-β1. The role of ADSCs-EVs in frostbite wound healing was also confirmed in vivo. ADSCs-EVs could promote frostbite wound healing by downregulating the expression of SOCS3 and upregulating the expression of TGF-β1 and collagen I. Conclusion: Collectively, ADSCs-EVs inhibit SOCS3 and facilitate the expression of TGF-β1, which promotes the proliferation and migration of HSF cells and subsequently enhances wound healing of frostbite injury.

Objective: The aim of the present study was to investigate the protective effect of MSCs on CLP-induced SA-AKI and determine the mechanisms of this effect. Methods: The expression of Gal-9 and Tim-3 was assayed by qPCR and western blot. IL-10, IL-17, RORγt, and FOXP3 were assayed by qPCR and TNFα, INFγ, IL-4, and IL-6 were assayed by ELISA in renal samples after CLP with or without MSCs treatment. The expression of Gal-9 in MSCs was knocked down in vivo using RNA interference, and si-Gal-9-MSCs were injected in SA-AKI mice. The effect of MSCs on the differentiation of lymphocytes into Th17 cells and Tregs was evaluated in vitro by FAC in coculture of MSCs and CD4+ T cells and after blockade of the Gal-9/Tim-3 pathway. Results: MSCs decreased serum creatinine and urea nitrogen levels and relieved tubular injury. Additionally, MSCs significantly improved the survival rate and markedly attenuated the infiltration of neutrophils and the levels of TNF-α, IFN-γ, IL-4, and IL-6 in the kidneys of septic mice (P < 0.05). Treatment with MSCs also reduced the proportion of Th17 cells and the levels of IL-17 and RORγt (P < 0.05). In contrast, MSCs increased the proportion of Tregs and the levels of IL-10 and FOXP3 related to these cells (P < 0.05). Furthermore, we determined whether Gal-9/Tim-3 and Th17 cells/Tregs are involved in the protective effects of MSCs in an SA-AKI model. The results of Western blot and real-time PCR indicated that MSCs inhibited the expression of Tim-3 and increased the expression of gal-9 (P < 0.05). Knockdown of gal-9 in MSCs using small interfering RNA blunted the therapeutic effect of MSCs, and blockade of the Gal-9/Tim-3 pathway using α-lactose or anti-Tim-3 inhibited the induction of Tregs and suppressed the inhibition of the differentiation to Th17 cells by MSCs after coculture of MSCs with CD4+ T cells (P > 0.05). Conclusion: Treatment with MSCs can protect against SA-AKI. The results suggested that the relieving effect of MSCs against SA-AKI may be partially mediated by the induction of Tregs and inhibition of Th17 cells via the Gal-9/Tim-3 pathway.

Background: Human pluripotent stem cell (hPSC)-derived kidney organoids may contribute to disease modeling and the generation of kidney replacement tissues. However, the realization of such applications requires the induction of hPSCs into functional mature organoids. One of the key questions for this process is whether a specific vascular system exists for nephrogenesis. Our previous study showed that short-term (2 weeks) implantation of hPSC-derived organoids below the kidney capsules of unilaterally nephrectomized and immunodeficient mice resulted in the enlargement of organoids and production of vascular cells, although signs of maturation were lacking. Methods: Organoids were induced for 15 days in vitro and then grafted below kidney capsules of the same unilaterally nephrectomized immunodeficient mouse model to examine whether medium-term (4 weeks) implantation could improve organoid maturation and vascularization, as evaluated by immunofluorescence and transmission electron microscopy. Results: We demonstrated that after 2–4 weeks of implantation, renal organoids formed host-derived vascularization and matured without any exogenous vascular endothelial growth factor. Glomerular filtration barrier maturation was evidenced by glomerular basement membrane deposition, perforated glomerular endothelial cell development, and apical, basal podocyte polarization. A polarized monolayer epithelium and extensive brush border were also observed for tubular epithelial cells. Conclusions: Our results indicate that the in vivo microenvironment is important for the maturation of human kidney organoids. Stromal expansion and a reduction of nephron structures were observed following longer-term (12 weeks) implantation, suggesting effects on off-target cells during the induction process. Accordingly, induction efficiency and transplantation models should be improved in the future.

Background: Pulp regeneration is a promising strategy that promotes the continued development of young permanent teeth with immature apical foramen. Platelet-rich fibrin (PRF) was found to stimulate the proliferation and differentiation of osteoblasts, but its effects on osteoblast/odontoblast differentiation of human dental pulp stem cells (hDPSCs) are unknown. Methods: The hDPSCs were isolated and identified using known surface markers by flow cytometry. The CCK-8 assay and the expression of Ki67 and PCNA were used to examine hDPSC proliferation. After 7 days of culture in an osteo-/odontoblastic induction medium with various concentrations of liquid PRF (0, 10% and 20%), the early stage of osteogenesis-intracellular alkaline phosphatase (ALP) was checked. After 21 days of culture, matrix mineralization was checked using Alizarin Red S and quantified. The mRNA and protein levels of osteo-/odontoblastic genes, including RUNX2, DSPP, DMP1 and BSP, were measured by qRT-PCR. The notch signal was checked by Western blot to analyze three key proteins (Notch 1, Jagged 1 and Hes 1). Results: PRF-treated groups showed higher expression of Ki-67 and PCNA, higher ALP activity, and the higher dose showed a stronger induction. PRF promoted osteo-/odontoblastic differentiation of hDPSCs indicated by elevated protein levels and mRNA levels of the expression of osteo-/odontoblastic markers. The three key proteins in Notch signaling showed an increase compared with the control group and increased as the PRF concentration increased. Conclusion: PRF can promote the proliferation and osteo-/odontoblastic differentiation of hDPSC, which may be through the Notch signaling pathway.

Backgrond: Novel scaffolds and stem cells are alternatives for the treatment of spinal cord injury (SCI), which causes life-long disability. However, there is a lack of synthesized evidence comparing different therapies. Aim: To examine the efficacy of various treatments in achieving locomotor recovery in SCI animals. The PubMed, Scopus and Web of Science databases were searched from inception to 21st May 2021. Methods: The data were extracted by one investigator under the surveillance of a referee according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 statement and stored in Microsoft Excel. All data were analysed using Bayesian network analysis with a consistency model. The selection was performed in strict accordance with the participant, intervention, comparison, outcome and study (PICOS) principle, as specifically stated in the methods section. Results: A total of 387 eligible studies involving 11169 animals subjected to 5 different treatments were evaluated. Compared to placebo or no treatment, scaffolds (mean difference (MD), 2.04; 95% credible interval (CrI): 1.58 to 2.50), exosomes (MD, 3.46; 95% CrI: 3.07 to 3.86), stem cells (MD, 4.18; 95% CrI: 3.28 to 5.07), scaffolds in conjunction with stem cells (MD, 5.26; 95% CrI: 4.62 to 5.89), and scaffolds in conjunction with non-cell agents (MD, 4.88; 95% CrI: 4.21 to 5.54) led to significant recovery of locomotor function in SCI animals. No significant difference in the locomotor function score was observed between animals treated with stem cells and those treated with exosomes (MD, 0.71; 95% CrI: -0.25 to 3.05), between animals treated with scaffolds in conjunction with stem cells and those treated with scaffolds in conjunction with non-cell agents (MD, -0.38; 95% CrI: -1.24 to 0.49), or between animals treated with scaffolds in conjunction with non-cell agents and those treated with stem cells (MD, 0.71; 95% CrI: - 0.38 to 1.80). Conclusion: Significant differences in the efficacy of various therapies in SCI animals were observed, and transplantation of scaffolds in conjunction with non-cell agents, scaffolds in conjunction with stem cells, and stem cells should be considered over transplantation of exosomes or scaffolds alone. Even though transplantation of scaffolds alone promoted locomotor function recovery in SCI animals, its use should be discouraged.