Mesenchymal stem cell dysfunction in diabetes

Human Periodontal Ligament Stem Cells (hPDLSCs) Spontaneously Differentiate into Myofibroblasts to Repair Diabetic Wounds

Advanced glycation end product (AGE) accumulation due to diabetes causes vascular and neurological lesions, delaying healing. The use of stem cells could overcome these problems. Although many studies have shown the potential beneficial effects of stem cell therapies in the treatment of chronic and refractory skin ulcers, their delivery methods are still under investigation. Human periodontal ligament stem cells (hPDLSCs) can spontaneously differentiate into myofibroblasts in specific cultures; therefore, they have the potential to effectively treat diabetic wounds and may also have applications in the field of medical cosmetics. The myofibroblastic differentiation ability of hPDLSCs in the presence of AGEs was evaluated by the expression of α-SMA and COL1A1 using RT-qPCR and WB technology. Wound healing in diabetic mice, induced by streptozotocin (STZ) and assessed using H&E staining, Masson staining, and immunohistochemical (IHC) and immunofluorescence (IF) staining, was used to validate the effects of hPDLSCs. In the wound tissues, the expression of α-SMA, COL1A1, CD31, CD206, iNOS, and vimentin was detected. The findings indicated that in H-DMEM, the expression of COL1A1 exhibited a significant decrease, while α-SMA demonstrated an increase in P7 cells, ignoring the damage from AGEs (p < 0.05). In an STZ-induced diabetic C57BL/6J mice whole-skin defect model, the healing rate of the hPDLSCs treatment group was significantly higher than that in the models (on the 7th day, the rate was 65.247% vs. 48.938%, p < 0.05). hPDLSCs have been shown to spontaneously differentiate into myofibroblasts in H-DMEM and resist damage from AGEs in both in vivo and in vitro models, suggesting their potential in the field of cosmetic dermatology.

Autophagy, a double-edged sword for oral tissue regeneration

BACKGROUND

Oral health is of fundamental importance to maintain systemic health in humans. Stem cell-based oral tissue regeneration is a promising strategy to achieve the recovery of impaired oral tissue. As a highly conserved process of lysosomal degradation, autophagy induction regulates stem cell function physiologically and pathologically. Autophagy activation can serve as a cytoprotective mechanism in stressful environments, while insufficient or over-activation may also lead to cell function dysregulation and cell death.

AIM OF REVIEW

This review focuses on the effects of autophagy on stem cell function and oral tissue regeneration, with particular emphasis on diverse roles of autophagy in different oral tissues, including periodontal tissue, bone tissue, dentin pulp tissue, oral mucosa, salivary gland, maxillofacial muscle, temporomandibular joint, etc. Additionally, this review introduces the molecular mechanisms involved in autophagy during the regeneration of different parts of oral tissue, and how autophagy can be regulated by small molecule drugs, biomaterials, exosomes/RNAs or other specific treatments. Finally, this review discusses new perspectives for autophagy manipulation and oral tissue regeneration.

KEY SCIENTIFIC CONCEPTS OF REVIEW

Overall, this review emphasizes the contribution of autophagy to oral tissue regeneration and highlights the possible approaches for regulating autophagy to promote the regeneration of human oral tissue.

The treatment efficacy of bone tissue engineering strategy for repairing segmental bone defects under diabetic condition

Background

Diabetes mellitus is a systematic disease which exert detrimental effect on bone tissue. The repair and reconstruction of bone defects in diabetic patients still remain a major clinical challenge. This study aims to investigate the potential of bone tissue engineering approach to improve bone regeneration under diabetic condition.

Methods

In the present study, decalcified bone matrix (DBM) scaffolds were seeded with allogenic fetal bone marrow-derived mesenchymal stem cells (BMSCs) and cultured in osteogenic induction medium to fabricate BMSC/DBM constructs. Then the BMSC/DBM constructs were implanted in both subcutaneous pouches and large femoral bone defects in diabetic (BMSC/DBM in DM group) and non-diabetic rats (BMSC/DBM in non-DM group), cell-free DBM scaffolds were implanted in diabetic rats to serve as the control group (DBM in DM group). X-ray, micro-CT and histological analyses were carried out to evaluate the bone regenerative potential of BMSC/DBM constructs under diabetic condition.

Results

In the rat subcutaneous implantation model, quantitative micro-CT analysis demonstrated that BMSC/DBM in DM group showed impaired bone regeneration activity compared with the BMSC/DBM in non-DM group (bone volume: 46 ± 4.4 mm3 vs 58.9 ± 7.15 mm3, *p < 0.05). In the rat femoral defect model, X-ray examination demonstrated that bone union was delayed in BMSC/DBM in DM group compared with BMSC/DBM in non-DM group. However, quantitative micro-CT analysis showed that after 6 months of implantation, there was no significant difference in bone volume and bone density between the BMSC/DBM in DM group (199 ± 63 mm3 and 593 ± 65 mg HA/ccm) and the BMSC/DBM in non-DM group (211 ± 39 mm3 and 608 ± 53 mg HA/ccm). Our data suggested that BMSC/DBM constructs could repair large bone defects in diabetic rats, but with delayed healing process compared with non-diabetic rats.

Conclusion

Our study suggest that biomaterial sacffolds seeded with allogenic fetal BMSCs represent a promising strategy to induce and improve bone regeneration under diabetic condition.

Revolutionizing Diabetic Foot Ulcer Care: The Senotherapeutic Approach

Diabetic foot ulcers (DFUs) are a prevalent and profoundly debilitating complication that afflicts individuals with diabetes mellitus (DM). These ulcers are associated with substantial morbidity, recurrence rates, disability, and mortality, imposing substantial economic, psychological, and medical burdens. Timely detection and intervention can mitigate the morbidity and disparities linked to DFU. Nevertheless, current therapeutic approaches for DFU continue to grapple with multifaceted limitations. A growing body of evidence emphasizes the crucial role of cellular senescence in the pathogenesis of chronic wounds. Interventions that try to delay cellular senescence, eliminate senescent cells (SnCs), or suppress the senescence-associated secretory phenotype (SASP) have shown promise for helping chronic wounds to heal. In this context, targeting cellular senescence emerges as a novel therapeutic strategy for DFU. In this comprehensive review, we look at the pathology and treatment of DFU in a systematic way. We also explain the growing importance of investigating SnCs in DFU and highlight the great potential of senotherapeutics that target SnCs in DFU treatment. The development of efficacious and safe senotherapeutics represents a pioneering therapeutic approach aimed at enhancing the quality of life for individuals affected by DFU.

Influence of Reactive Oxygen Species on Wound Healing and Tissue Regeneration in Periodontal and Peri-Implant Tissues in Diabetic Patients

Diabetes mellitus (DM) is associated with periodontal disease. Clinically, periodontal treatment is less effective for patients with DM. Oxidative stress is one of the mechanisms that link DM to periodontitis. The production of reactive oxygen species (ROS) is increased in the periodontal tissues of patients with DM and is involved in the development of insulin resistance in periodontal tissues. Insulin resistance decreases Akt activation and inhibits cell proliferation and angiogenesis. This results in the deterioration of wound healing and tissue repair in periodontal tissues. Antioxidants and insulin resistance ameliorants may inhibit ROS production and improve wound healing, which is worsened by DM. This manuscript provides a comprehensive review of the most recent basic and clinical evidence regarding the generation of ROS in periodontal tissues resulting from microbial challenge and DM. This study also delves into the impact of oxidative stress on wound healing in the context of periodontal and dental implant therapies. Furthermore, it discusses the potential benefits of administering antioxidants and anti-insulin resistance medications, which have been shown to counteract ROS production and inflammation. This approach may potentially enhance wound healing, especially in cases exacerbated by hyperglycemic conditions.

The stereological, immunohistological, and gene expression studies in an infected ischemic wound in diabetic rats treated by human adipose-derived stem cells and photobiomodulation

We investigated the impacts of photobiomodulation (PBM) and human allogeneic adipose-derived stem cells (ha-ADS) together and or alone applications on the stereological parameters, immunohistochemical characterizing of M1 and M2 macrophages, and mRNA levels of hypoxia-inducible factor (HIF-1α), basic fibroblast growth factor (bFGF), vascular endothelial growth factor-A (VEGF-A) and stromal cell-derived factor-1α (SDF-1α) on inflammation (day 4) and proliferation phases (day 8) of repairing tissues in an infected delayed healing and ischemic wound model (IDHIWM) in type 1 diabetic (DM1) rats. DM1 was created in 48 rats and an IDHIWM was made in all of them, and they were distributed into 4 groups. Group1 = control rats with no treatment. Group2 = rats received (10 × 100000 ha-ADS). Group3 = rats exposed to PBM (890 nm, 80 Hz, 3.46 J/cm2). Group4 = rats received both PBM and ha-ADS. On day 8, there were significantly higher neutrophils in the control group than in other groups (p < 0.01). There were substantially higher macrophages in the PBM + ha-ADS group than in other groups on days 4 and 8 (p < 0.001). Granulation tissue volume, on both days 4 and 8, was meaningfully greater in all treatment groups than in the control group (all, p = 0.000). Results of M1 and M2 macrophage counts of repairing tissue in the entire treatment groups were considered preferable to those in the control group (p < 0.05). Regarding stereological and macrophage phenotyping, the results of the PBM + ha-ADS group were better than the ha-ADS and PBM groups. Results of the tested gene expression of repairing tissue on inflammation and proliferation steps in PBM and PBM + ha-ADS groups were meaningfully better than the control and ha-ADS groups (p < 0.05). We showed that PBM, ha-ADS, and PBM plus ha-ADS, hastened the proliferation step of healing in an IDHIWM in rats with DM1 by regulation of the inflammatory reaction, macrophage phenotyping, and augmented granulation tissue formation. In addition PBM and PBM plus ha-ADS protocols hastened and increased mRNA levels of HIF-1α, bFGF, SDF-1α, and VEGF-A. Totally, in terms of stereological and immuno-histological tests, and also gene expression HIF-1α and VEGF-A, the results of PBM + ha-ADS were superior (additive) to PBM, and ha-ADS alone treatments.

Icariin promotes the proliferation and osteogenic differentiation of bone-derived mesenchymal stem cells in patients with osteoporosis and T2DM by upregulating GLI-1

BACKGROUND

The function of mesenchymal stem cells (MSCs) from patients with osteoporosis (OP) is impaired and worsens in patients with type 2 diabetes mellitus (T2DM). Icariin (ICA) is the major active flavonoid glucoside isolated from traditional Chinese herbal Epimedium pubescens, and confirmed able to improve bone mass of OP patients.

OBJECTIVE

To investigate the effect of ICA on the proliferation and osteogenic differentiation of bone-derived MSCs (BMSCs) from patients with OP and T2DM and uncover the potential mechanism.

METHODS

BMSCs were treated with ICA, and proliferation and osteogenic potency were evaluated using the 2,5-diphenyl-2H-tetrazolium bromide (MTT) assay and detection of osteogenic markers (ALP, RUNX2, SPP1, COL1A1, and mineralized nodules) was performed. RNA sequencing and bioinformatic analysis were performed to identify differentially expressed genes (DEGs) after ICA treatment and screen proliferation- and osteogenic differentiation-related processes. Gene gain and loss were performed to confirm the role of the key candidate gene.

RESULTS

ICA significantly promoted the proliferation and osteogenic differentiation of BMSCs. A total of 173 DEGs were identified after ICA treatment. Six DEGs (GLI-1, IGF2, BMP6, WNT5A, PTHLH, and MAPK14) enriched in both proliferation- and osteogenic differentiation-related processes were screened; GLI-1 had the highest validated |log2FC| value. Overexpression of GLI-1 enhanced the proliferation and osteogenic differentiation of BMSCs, and knockdown of GLI-1 weakened the positive effect of ICA on BMSCs.

CONCLUSION

ICA promoted the proliferation and osteogenic differentiation of impaired BMSCs by upregulating GLI-1.

Iron metabolism and ferroptosis in diabetic bone loss: from mechanism to therapy

Osteoporosis, one of the most serious and common complications of diabetes, has affected the quality of life of a large number of people in recent years. Although there are many studies on the mechanism of diabetic osteoporosis, the information is still limited and there is no consensus. Recently, researchers have proven that osteoporosis induced by diabetes mellitus may be connected to an abnormal iron metabolism and ferroptosis inside cells under high glucose situations. However, there are no comprehensive reviews reported. Understanding these mechanisms has important implications for the development and treatment of diabetic osteoporosis. Therefore, this review elaborates on the changes in bones under high glucose conditions, the consequences of an elevated glucose microenvironment on the associated cells, the impact of high glucose conditions on the iron metabolism of the associated cells, and the signaling pathways of the cells that may contribute to diabetic bone loss in the presence of an abnormal iron metabolism. Lastly, we also elucidate and discuss the therapeutic targets of diabetic bone loss with relevant medications which provides some inspiration for its cure.

Implantation of CPT1AM-expressing adipocytes reduces obesity and glucose intolerance in mice

Obesity and its associated metabolic comorbidities are a rising global health and social issue, with novel therapeutic approaches urgently needed. Adipose tissue plays a key role in the regulation of energy balance and adipose tissue-derived mesenchymal stem cells (AT-MSCs) have gained great interest in cell therapy. Carnitine palmitoyltransferase 1A (CPT1A) is the gatekeeper enzyme for mitochondrial fatty acid oxidation. Here, we aimed to generate adipocytes expressing a constitutively active CPT1A form (CPT1AM) that can improve the obese phenotype in mice after their implantation. AT-MSCs were differentiated into mature adipocytes, subjected to lentivirus-mediated expression of CPT1AM or the GFP control, and subcutaneously implanted into mice fed a high-fat diet (HFD). CPT1AM-implanted mice showed lower body weight, hepatic steatosis and serum insulin and cholesterol levels alongside improved glucose tolerance. HFD-induced increases in adipose tissue hypertrophy, fibrosis, inflammation, endoplasmic reticulum stress and apoptosis were reduced in CPT1AM-implanted mice. In addition, the expression of mitochondrial respiratory chain complexes was enhanced in the adipose tissue of CPT1AM-implanted mice. Our results demonstrate that implantation of CPT1AM-expressing AT-MSC-derived adipocytes into HFD-fed mice improves the obese metabolic phenotype, supporting the future clinical use of this ex vivo gene therapy approach.

MicroRNA-139-5p mediates BMSCs impairment in diabetes by targeting HOXA9/c-Fos

The properties and functions of BMSCs were altered by the diabetic microenvironment, and its mechanism was not very clear. In recent years, the regulation of the function of BMSCs by microRNA has become a research hotspot, meanwhile, HOX genes also have been focused on and involved in multiple functions of stem cells. In this study, we investigated the role of miR-139-5p in diabetes-induced BMSC impairment. Since HOXA9 may be a target gene of miR-139-5p, we speculated that miR-139-5p/HOXA9 might be involved in regulating the biological characteristics and the function of BMSCs in diabetes. We demonstrated that the miR-139-5p expression was increased in BMSCs derived from STZ-induced diabetic rats. MiR-139-5p mimics were able to inhibit cell proliferation, and migration and promoted senescence and apoptosis in vitro. MiR-139-5p induced the down-regulated expression of HOXA9 and c-Fos in BMSCs derived from normal rats. Moreover, miR-139-5p inhibitors reversed the tendency in diabetic-derived BMSCs. Further, gain-and-loss function experiments indicated that miR-139-5p regulated the functions of BMSCs by targeting HOXA9 and c-Fos. In vivo wound model experiments showed that the downregulation of miR-139-5p further promoted the epithelialization and angiogenesis of diabetic BMSC-mediated skin. In conclusion, induction of miR-139-5p upregulation mediated the impairment of BMSCs through the HOXA9/c-Fos pathway in diabetic rats. Therefore, miR-139-5p/HOXA9 might be an important therapeutic target in treating diabetic BMSCs and diabetic complications in the future.

Marrow changes and reduced proliferative capacity of mesenchymal stromal cells from patients with "no-option" critical limb ischemia; observations on feasibility of the autologous approach from a clinical trial

BACKGROUND AIMS

Approximately 1 in 3 patients with critical limb ischemia (CLI) are not suitable for surgical or endovascular revascularization. Those "no-option" patients are at high risk of amputation and death. Autologous bone marrow mesenchymal stromal cells (MSCs) may provide a limb salvage option. In this study, bone marrow characteristics and expansion potentials of CLI-derived MSCs produced during a phase 1b clinical trial were compared with young healthy donor MSCs to determine the feasibility of an autologous approach. Cells were produced under Good Manufacturing Practice conditions and underwent appropriate release testing.

METHODS

Five bone marrow aspirates derived from patients with CLI were compared with six young healthy donor marrows in terms of number of colony-forming units-fibroblast (CFUF) and mononuclear cells. The mean population doubling times and final cell yields were used to evaluate expansion potential. The effect of increasing the volume of marrow on the CFUF count and final cell yield was evaluated by comparing 5 CLI-derived MSCs batches produced from a targeted 30 mL of marrow aspirate to five batches produced from a targeted 100 mL of marrow.

RESULTS

CLI-derived marrow aspirate showed significantly lower numbers of mononuclear cells with no difference in the number of CFUFs when compared with healthy donors' marrow aspirate. CLI-derived MSCs showed a significantly longer population doubling time and reduced final cell yield compared with young healthy donors' MSCs. The poor growth kinetics of CLI MSCs were not mitigated by increasing the bone marrow aspirate from 30 to 100 mL.

CONCLUSIONS

In addition to the previously reported karyotype abnormalities in MSCs isolated from patients with CLI, but not in cells from healthy donors, the feasibility of autologous transplantation of bone marrow MSCs for patients with no-option CLI is further limited by the increased expansion time and the reduced cell yield.

Photobiomodulation isolated or associated with adipose-derived stem cells allograft improves inflammatory and oxidative parameters in the delayed-healing wound in streptozotocin-induced diabetic rats

The single and associated impressions of photobiomodulation (PBM) and adipose-derived stem cells (ADS) on stereological parameters (SP), and gene expression (GE) of some antioxidant and oxidative stressors of repairing injured skin at inflammation and proliferation steps (days 4 and 8) of a delayed healing, ischemic, and infected wound model (DHIIWM) were examined in type one diabetic (DM1) rats. DM1 was induced by administration of streptozotocin (40 mg/kg) in 48 rats. The DHIIWM was infected by methicillin-resistant Staphylococcus aureus (MRSA). The study comprised 4 groups (each, n = 6): Group 1 was the control group (CG). Group 2 received allograft human (h) ADSs transplanted into the wound. In group 3, PBM (890 nm, 80 Hz, 0.2 J/cm²) was emitted, and in group 4, a combination of PBM+ADS was used. At both studied time points, PBM+ADS, PBM, and ADS significantly decreased inflammatory cell count (p < 0.05) and increased granulation tissue formation compared to CG (p < 0.05). Similarly, there were lower inflammatory cells, as well as higher granulation tissue in the PBM+ADS compared to those of alone PBM and ADS (all, p < 0.001). At both studied time points, the GE of catalase (CAT) and superoxide dismutase (SOD) was remarkably higher in all treatment groups than in CG (p < 0.05). Concomitantly, the outcomes of the PBM+ADS group were higher than the single effects of PBM and ADS (p < 0.05). On day 8, the GE of NADPH oxidase (NOX) 1 and NOX4 was substantially less in the PBM+ADS than in the other groups (p < 0.05). PBM+ADS, PBM, and ADS treatments significantly accelerated the inflammatory and proliferative stages of wound healing in a DIIWHM with MRSA in DM1 rats by decreasing the inflammatory response, and NOX1 and 4 as well; and also increasing granulation tissue formation and SOD and CAT. The associated treatment of PBM+ADS was more effective than the individual impacts of alone PBM and ADS because of the additive anti-inflammatory and proliferative effects of PBM plus ADS treatments.

Mesenchymal Stromal Cell Exosomes in Cardiac Repair

PURPOSE OF THE REVIEW

Mesenchymal stromal cells (MSCs) are considered an attractive option for cell-based therapy because of their immune-privileged phenotype and paracrine activity. Substantial preclinical evidence indicates that MSC exosomes recapitulate MSC cellular function in cardiac regeneration and repair. Therefore, in this review, we briefly discuss the latest research progress of MSC exosomes in cardiac repair and regeneration.

RECENT FINDINGS

The recent revolutionary advance in controlling the contents of the exosomes by manipulating parental cells through bioengineering methods to alter specific signaling pathways in ischemic myocardium has proven to be beneficial in the treatment of heart failure. MSC Exosomes appear to be leading candidates to treat myocardial infarction and subsequent heart failure by carrying rich cargo from their parental cells. However, more clinical and pre-clinical studies on MSC exosomes will be required to confirm the beneficial effect to treat cardiovascular diseases.

Hypoxia preconditioning increases the ability of healthy but not diabetic rat-derived adipose stromal/stem cells (ASC) to improve histological lesions of streptozotocin-induced diabetic nephropathy

BACKGROUND

Mesenchymal stromal cells (MSC) have demonstrated ability to improve diabetic nephropathy (DN) in experimental models, as well as by improving kidney endogenous progenitor cells proliferation and differentiation. Many studies have demonstrated the effect of hypoxia on MSC improving their functionality but the potential enhancement of the nephroprotective properties of MSC cultured under low oxygen concentration has been explored in few studies, none of them in the context of DN. On the other hand, diabetes is associated with abnormalities in MSCs functionality. These findings related to the hypoxia preconditioning ability to enhance adipose-tissue derived-MSC (ASC) performance have led us to wonder if hypoxia could increase the known beneficial effect of normal ASC in DN and if it could correct the expected inability of diabetic rat-derived ASC to exert this effect in vivo. To answer these questions, in the present study we have used ASC from healthy and diabetic-induced rats, cultured under standard conditions or hypoxia preconditioned, in a DN rat model induced by streptozotocin (STZ).

METHODS

Diabetes was induced in Wistar-rats by 60 mg/kg streptozotocin (STZ) intraperitoneal injection. Fifteen days thereafter, five diabetic-induced rats and five healthy, previously injected with saline, were sacrificed and used as ASC donors . Both healthy and diabetic rat-derived ASC (cASC and dASC, respectively) were cultured under standard conditions (21%O2)(N) or were subjected to a 48 h conditioning period in hypoxia (3%O2)(H). Thus, four types of cells were generated depending on their origin (healthy or diabetic-induced rats) and the culture conditions(N or H):cASC-N, cASC-H, dASC-N and dASC-H. DN experimental study were carried out fifteen days after STZ induction of diabetes in fifty-two healthy rats. DN-induced-animals were randomly assigned to be injected with 200 µL saline as placebo or with 3 × 106 cASC-N, cASC-H, dASC-N or dASC-H, according to the study group. Serum glucose, urea and creatinine, and urine albumin levels were measured at 2-weeks intervals until day+ 45 after ND-induction.Animals were sacrificed and kidneys extracted for histopathological and transmission electron microcopy analysis RESULTS: None of the four study groups that received cell treatment showed significant changes in serum glucose, urea and creatinine levels, urine albumin concentration and body weight compared to placebo ND-induced group. Interestingly, only the group that received cASC-H showed a reduction in glucose and creatinine levels although it did not reach statistical significance.All DN-induced groups treated with ASC reduced significantly renal lesions such as mesangial expansion, mesangiolysis, microaneurysms and acute tubular necrosis compared to ND-induced placebo group (p ≤ 0.05). Renal injuries such as clear tubular cell changes, thickening of tubular basement membrane, tubular cysts and interstitial fibrosis significantly showed reduction in ND-induced rats treated with cASC-H regarding to their received cASCN (p ≤ 0.05). Non statistical differences were observed in the improvement capacity of cASC and dASC culture under standard condition.However, hypoxia preconditioning reduces the presence of tubular cysts (p ≤ 0.01).

CONCLUSIONS

Hypoxia preconditioning enhances the ability of healthy rat-derived ASC to improve kidney injury in a rat model of DN. Moreover, diabetic-derived ASC exhibits a similar ability to healthy ASC which is clearly more than expected, but it is not significantly modified by hypoxia preconditioning.

Impact of procedural variability and study design quality on the efficacy of cell-based therapies for heart failure - a meta-analysis

Background

Cell-based therapy has long been considered a promising strategy for the treatment of heart failure (HF). However, its effectiveness in the clinical setting is now doubted. Because previous meta-analyses provided conflicting results, we sought to review all available data focusing on cell type and trial design.

Methods and findings

The electronic databases PubMed, Cochrane library, ClinicalTrials.gov, and EudraCT were searched for randomized controlled trials (RCTs) utilizing cell therapy for HF patients from January 1, 2000 to December 31, 2020. Forty-three RCTs with 2855 participants were identified. The quality of the reported study design was assessed by evaluating the risk-of-bias (ROB). Primary outcomes were defined as mortality rate and left ventricular ejection fraction (LVEF) change from baseline. Secondary outcomes included both heart function data and clinical symptoms/events. Between-study heterogeneity was assessed using the I2 index. Subgroup analysis was performed based on HF type, cell source, cell origin, cell type, cell processing, type of surgical intervention, cell delivery routes, cell dose, and follow-up duration. Only 10 of the 43 studies had a low ROB for all method- and outcome parameters. A higher ROB was associated with a greater increase in LVEF. Overall, there was no impact on mortality for up to 12 months follow-up, and a clinically irrelevant average LVEF increase by LVEF (2.4%, 95% CI = 0.75−4.05, p = 0.004). Freshly isolated, primary cells tended to produce better outcomes than cultured cell products, but there was no clear impact of the cell source tissue, bone marrow cell phenotype or cell chricdose (raw or normalized for CD34+ cells). A meaningful increase in LVEF was only observed when cell therapy was combined with myocardial revascularization.

Conclusions

The published results suggest a small increase in LVEF following cell therapy for heart failure, but publication bias and methodologic shortcomings need to be taken into account. Given that cardiac cell therapy has now been pursued for 20 years without real progress, further efforts should not be made.

Study registry number

This meta-analysis is registered at the international prospective register of systematic reviews, number CRD42019118872.

Targeting Programmed Cell Death to Improve Stem Cell Therapy: Implications for Treating Diabetes and Diabetes-Related Diseases

Stem cell therapies have shown promising therapeutic effects in restoring damaged tissue and promoting functional repair in a wide range of human diseases. Generations of insulin-producing cells and pancreatic progenitors from stem cells are potential therapeutic methods for treating diabetes and diabetes-related diseases. However, accumulated evidence has demonstrated that multiple types of programmed cell death (PCD) existed in stem cells post-transplantation and compromise their therapeutic efficiency, including apoptosis, autophagy, necroptosis, pyroptosis, and ferroptosis. Understanding the molecular mechanisms in PCD during stem cell transplantation and targeting cell death signaling pathways are vital to successful stem cell therapies. In this review, we highlight the research advances in PCD mechanisms that guide the development of multiple strategies to prevent the loss of stem cells and discuss promising implications for improving stem cell therapy in diabetes and diabetes-related diseases.

The effect of photobiomodulation therapy on antioxidants and oxidative stress profiles of adipose derived mesenchymal stem cells in diabetic rats

We studied the effects of photobiomodulation therapy (PBMT) on adipose-derived mesenchymal stem cells (ADSCs) which were extracted from streptozotocin (STZ) induced diabetic rats. Adipose tissue was extracted from the hypodermis of diabetic rats, and diabetic ADSCs were extracted, characterized, and cultured. There were two in vitro groups: control-diabetic ADSCs, and PBMT-diabeticADSCs. We used 630 nm and 810 nm laser at 1.2 J/cm² with 3 applications 48 h apart. We measured cell viability, apoptosis, population doubling time (PDT), and reactive oxygen species (ROS) by flow cytometry. Gene expression of antioxidants, including cytosolic copper-zinc superoxide dismutase (SOD1), catalase (CAT), total antioxidant capacity (TAC), and oxidative stress biomarkers (NADPH oxidase 1 and 4) by quantitative real time (qRT) - PCR. In this study, data were analyzed using t-test. Viability of PBMT-diabetic- ADSC group was higher than control- diabetic-ADSC (p = 0.000). PDT and apoptosis of PBMT- diabetic-ADSC group were lower than control-diabetic -ADSC (p = 0.001, p = 0.02). SOD1 expression and TAC of PBMT- diabetic-ADSC group were higher than control -diabetic -ADSC (p = 0.018, p = 0.005). CAT of PBMT -diabetic-ADSC group was higher than control-diabetic -ADSC. ROS, NOX1, and NOX4 of PBMT- diabetic -ADSC group were lower than control-diabetic-ADSC (p = 0.002, p = 0.021, p = 0.017). PBMT may improve diabetic- ADSC function in vitro by increasing levels of cell viability, and gene expression of antioxidant agents (SOD1, CAT, and TAC), and significantly decreasing of levels of PDT, apoptosis, ROS, and gene expression of oxidative stress biomarkers (NOX1 and NOX4).

The Effect of N-Acetylcysteine and Ascorbic Acid-2-Phosphate Supplementation on Mesenchymal Stem Cell Function in B6.C-Lepob/J Type 2 Diabetic Mice

Diabetes is a complex multifactorial disorder associated with hyperglycemia, oxidative stress, and inflammation. The pathological microenvironment impairs mesenchymal stem cell (MSC) viability and dysregulates their proregenerative and immune-modulatory function causing maladaptive tissue damage. Targeting stem cells to protect them against impairment could thus delay the onset of complications and enhance the quality of life in diabetes mellitus patients. The aim of this study was to investigate the efficacy of N-acetylcysteine (NAC) and ascorbic-acid-2-phosphate (AAP) oral supplementation as preventative measure against MSC impairment. Healthy wild-type control (C57BL/6J) (male, n = 24) and obese diabetic (B6.C-Lep^ob/J) (ob/ob) (male, n = 24) mice received either placebo or antioxidant (NAC/AAP) supplementation for a period of 6 weeks. Metabolic parameters (weight and blood glucose) and the oxidative status (serum total serum antioxidant capacity, malondialdehyde) of animals were assessed. At the end of the 6-week supplementation period, bone marrow MSCs were isolated and their functionality (growth rate, viability, adipogenesis, and osteogenesis) assessed ex vivo. Real time quantitative polymerase chain reaction microarray analysis was also performed to assess the expression of 84 genes related to oxidative stress in MSCs. Despite no change in the metabolic profile, NAC/AAP supplementation improved the antioxidant status of diabetic animals and reduced lipid peroxidation, which is indicative of cellular damage. NAC/AAP also improved the population doubling time of MSCs (first 6-days postisolation) and significantly downregulated the expression of two genes (Nox1 and Rag2) associated with oxidative stress compared to placebo treatment. Taken together, this study has shown reduced oxidative stress and improvements in MSC function following in vivo antioxidant supplementation in healthy control and type 2 diabetic mice.

Nerve growth factor enhances the therapeutic effect of mesenchymal stem cells on diabetic periodontitis

Patients with diabetes frequently suffer from periodontitis, which progresses rapidly and is difficult to cure. Mesenchymal stem cell (MSC) transplantation may effectively treat periodontitis, but high glucose limits its therapeutic effect in diabetes. Nerve growth factor (NGF) has the functions of cell protection, anti-apoptosis and immune regulation, and may have potential application in diabetic periodontitis. In the present study, flow cytometry indicated that NGF inhibited MSC apoptosis induced by high glucose. Of note, high glucose promoted the transformation of MSCs into the proinflammatory type. NGF inhibited this transformation of MSCs under diabetic conditions and further decreased the proportion of T cells and monocytes/macrophages among lymphocytes. An animal model of diabetic periodontitis was constructed and MSC transplantation was demonstrated to reduce alveolar bone loss caused by diabetes. NGF enhanced the therapeutic effect of MSCs and maintained transplanted MSC survival in periodontal tissue of diabetic mice. Immunohistochemical analysis of periodontal tissues suggested that in the NGF group, infiltration of T cells and macrophages was reduced. Neurotrophic receptor tyrosine kinase 1 was indicated to have a key role in these effects of NGF. In conclusion, NGF may enhance the therapeutic effect of MSCs on diabetic periodontitis by protecting the cells and promoting the transformation of MSCs into the immunosuppressive type.

Role of iron and iron-related proteins in mesenchymal stem cells: Cellular and clinical aspects

Mesenchymal stem cells (MSCs) are located in various tissues where these cells show niche-dependent multilineage differentiation and secrete immunomodulatory molecules to support numerous physiological processes. Due to their regenerative and reparative properties, MSCs are extremely valuable for cell-based therapy in tackling several pathological conditions including COVID-19. Iron is essential for MSC processes but iron-loading, which is common in several chronic conditions, hinders normal MSC functionality. This not only aggravates disease pathology but can also affect allogeneic and autologous MSC therapy. Thus, understanding MSCs from an iron perspective is of clinical significance. Accordingly, this review highlights the roles of iron and iron-related proteins in MSC physiology. It describes the contribution of iron and endogenous iron-related effectors like hepcidin, ferroportin, transferrin receptor, lactoferrin, lipocalin-2, bone morphogenetic proteins and hypoxia inducible factors in MSC biology. It summarises the excess-iron-induced alterations in MSC components, processes and discusses signalling pathways involving ROS, PI3K/AKT, MAPK, p53, AMPK/MFF/DRP1 and Wnt. Additionally, it evaluates the endogenous and exogenous saviours of MSCs against iron-toxicity. Lastly, it elaborates on the involvement of MSCs in the pathology of clinical conditions of iron-excess, namely, hereditary hemochromatosis, diabetes, β-thalassaemia and myelodysplastic syndromes. This unique review integrates the distinct fields of iron regulation and MSC physiology. Through an iron-perspective, it describes both mechanistic and clinical aspects of MSCs and proposes an iron-linked MSC-contribution to physiology, pathology and therapeutics. It advances the understanding of MSC biology and may aid in identifying signalling pathways, molecular targets and compounds for formulating adjunctive iron-based therapies for excess-iron conditions, and thereby inform regenerative medicine.

Characterizing the degeneration of nuclear membrane and mitochondria of adipose-derived mesenchymal stem cells from patients with type II diabetes

Regenerative therapeutic approaches involving the transplantation of stem cells differentiated into insulin‐producing cells are being studied in patients with rapidly progressing severe diabetes. Adipose‐derived mesenchymal stem cells have been reported to have varied cellular characteristics depending on the biological environment of the location from which they were harvested. However, the characteristics of mesenchymal stem cells in type II diabetes have not been clarified. In this study, we observed the organelles of mesenchymal stem cells from patients with type II diabetes under a transmission electron microscope to determine the structure of stem cells in type II diabetes. Transmission electron microscopic observation of mesenchymal stem cells from healthy volunteers (N‐ADSC) and those from patients with type II diabetes (T2DM‐ADSC) revealed enlarged nuclei and degenerated mitochondrial cristae in T2DM‐ADSCs. Moreover, T2DM‐ADSCs were shown to exhibit a lower expression of Emerin, a constituent protein of the nuclear membrane, and a decreased level of mitochondrial enzyme activity. In this study, we successfully demonstrated the altered structure of nuclear membrane and the decreased mitochondrial enzyme activity in adipose‐derived mesenchymal cells from patients with type II diabetes. These findings have contributed to the understanding of type II diabetes‐associated changes in mesenchymal stem cells used for regenerative therapy.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Direct comparison of the immunogenicity of major histocompatibility complex-I and -II deficient mesenchymal stem cells in vivo

Mesenchymal stem cells (MSCs) play an important role in tissue engineering applications aiming at the regeneration or substitution of damaged tissues. In this context, off-the-shelf allogeneic MSCs would represent an attractive universal cell source. However, immune rejection is a major limitation for the clinical use of allogeneic MSCs. Immune rejection is mediated by the expression of major histocompatibility complexes (MHC)-I and -II on the donor cells. In this study, we eliminated MHC-I and/or MHC-II expression in human MSCs by using the CRISPR/Cas9 technology and investigated the effect of the individual or combined knockout of MHC-I and MHC-II on MSC survival after transplantation into immunocompetent mice. Elimination of MHC-I and/or MHC-II expression did not affect mesenchymal marker gene expression, viability, proliferation and the differentiation potential of MSCs in vitro. However, cell survival of transplanted MSCs was significantly elevated in MHC-I and MHC-II deficient MSCs. A direct side-by-side comparison does not reveal any significant difference in the immunogenicity of MHC-I and MHC-II knockout MSCs. Moreover, double knockout of MHC-I and MHC-II did not further increase in vivo cell survival of transplanted MSCs. Our results demonstrate that knockout of MHC-I and/or MHC-II represents an effective strategy to prevent immune rejection of allogeneic MSCs.

MiR-34a inhibitor protects mesenchymal stem cells from hyperglycaemic injury through the activation of the SIRT1/FoxO3a autophagy pathway

BACKGROUND

Mesenchymal stem cells (MSCs) are favourable treatments for ischaemic diseases; however, MSCs from diabetic patients are not useful for this purpose. Recent studies have shown that the expression of miR-34a is significantly increased in patients with hyperglycaemia; the precise role of miR-34a in MSCs in diabetes needs to be clarified.

OBJECTIVE

The aim of this study is to determine the precise role of miR-34a in MSCs exposed to hyperglycaemia and in recovery heart function after myocardial infarction (MI) in diabetes mellitus (DM) rats.

METHODS

DM rat models were established by high-fat diet combined with streptozotocin (STZ) injection. MSCs were isolated from the bone marrow of donor rats. Chronic culture of MSCs under high glucose was used to mimic the DM micro-environment. The role of miR-34a in regulating cell viability, senescence and paracrine effects were investigated using a cell counting kit-8 (CCK-8) assay, senescence-associated β-galactosidase (SA-β-gal) staining and vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) ELISA, respectively. The expression of autophagy- and senescence-associated proteins in MSCs and silent information regulator 1 (SIRT1) and forkhead box class O 3a (FoxO3a) were analysed by western blotting. Autophagic bodies were analysed by transmission electron microscopy (TEM). The MI model was established by left anterior descending coronary artery (LAD) ligation, and then, the rats were transplanted with differentially treated MSCs intramuscularly at sites around the border zone of the infarcted heart. Thereafter, cardiac function in rats in each group was detected via cardiac ultrasonography at 1 week and 3 weeks after surgery. The infarct size was determined through a 2,3,5-triphenyltetrazolium chloride (TTC) staining assay, while myocardial fibrosis was assessed by Masson staining.

RESULTS

The results of the current study showed that miR-34a was significantly increased under chronic hyperglycaemia exposure. Overexpression of miR-34a was significantly associated with impaired cell viability, exacerbated senescence and disrupted cell paracrine capacity. Moreover, we found that the mechanism underlying miR-34a-mediated deterioration of MSCs exposed to high glucose involved the activation of the SIRT1/FoxO3a autophagy pathway. Further analysis showed that miR-34a inhibitor-treated MSC transplantation could improve cardiac function and decrease the scar area in DM rats.

CONCLUSIONS

Our study demonstrates for the first time that miR-34a mediates the deterioration of MSCs' functions under hyperglycaemia. The underlying mechanism may involve the SIRT1/FoxO3a autophagy signalling pathway. Thus, inhibition of miR-34a might have important therapeutic implications in MSC-based therapies for myocardial infarction in DM patients.

Experimental Type 2 Diabetes Differently Impacts on the Select Functions of Bone Marrow-Derived Multipotent Stromal Cells

Bone marrow-derived multipotent stromal cells (BMMSCs) represent an attractive therapeutic modality for cell therapy in type 2 diabetes mellitus (T2DM)-associated complications. T2DM changes the bone marrow environment; however, its effects on BMMSC properties remain unclear. The present study aimed at investigating select functions and differentiation of BMMSCs harvested from the T2DM microenvironment as potential candidates for regenerative medicine. BMMSCs were obtained from Zucker diabetic fatty (ZDF; an obese-T2DM model) rats and their lean littermates (ZL; controls), and cultured under normoglycemic conditions. The BMMSCs derived from ZDF animals were fewer in number, with limited clonogenicity (by 2-fold), adhesion (by 2.9-fold), proliferation (by 50%), migration capability (by 25%), and increased apoptosis rate (by 2.5-fold) compared to their ZL counterparts. Compared to the cultured ZL-BMMSCs, the ZDF-BMMSCs exhibited (i) enhanced adipogenic differentiation (increased number of lipid droplets by 2-fold; upregulation of the Pparg, AdipoQ, and Fabp genes), possibly due to having been primed to undergo such differentiation in vivo prior to cell isolation, and (ii) different angiogenesis-related gene expression in vitro and decreased proangiogenic potential after transplantation in nude mice. These results provided evidence that the T2DM environment impairs BMMSC expansion and select functions pertinent to their efficacy when used in autologous cell therapies.

Characteristics and Therapeutic Potential of Human Amnion-Derived Stem Cells

Stem cells including embryonic stem cells (ESCs), induced pluripotent stem cells (iPSCs) and adult stem cells (ASCs) are able to repair/replace damaged or degenerative tissues and improve functional recovery in experimental model and clinical trials. However, there are still many limitations and unresolved problems regarding stem cell therapy in terms of ethical barriers, immune rejection, tumorigenicity, and cell sources. By reviewing recent literatures and our related works, human amnion-derived stem cells (hADSCs) including human amniotic mesenchymal stem cells (hAMSCs) and human amniotic epithelial stem cells (hAESCs) have shown considerable advantages over other stem cells. In this review, we first described the biological characteristics and advantages of hADSCs, especially for their high pluripotency and immunomodulatory effects. Then, we summarized the therapeutic applications and recent progresses of hADSCs in treating various diseases for preclinical research and clinical trials. In addition, the possible mechanisms and the challenges of hADSCs applications have been also discussed. Finally, we highlighted the properties of hADSCs as a promising source of stem cells for cell therapy and regenerative medicine and pointed out the perspectives for the directions of hADSCs applications clinically.

Investigation for GSK3β expression in diabetic osteoporosis and negative osteogenic effects of GSK3β on bone marrow mesenchymal stem cells under a high glucose microenvironment

Osteoporosis is a common skeletal complication of diabetes mellitus (DM). The mechanisms underlying the pathophysiology of diabetic osteoporosis are complex. Glycogen synthase kinase-3β (GSK-3β) is a widely expressed serine/threonine kinase and associated with both DM and bone metabolism, which arouse our concern. In this study, we established the diabetic mouse model by high-fat diet combined with streptozotocin injection. Decreased bone mass and reduced osteogenesis were observed in femurs of the mice. Besides, we identified that there is an activated expression of GSK3β in the bone marrow mesenchymal stem cells (BMSCs) of diabetic mice. To explore the link between GSK3β and diabetic osteoporosis, we exposed BMSCs to a high glucose microenvironment in vitro and discovered that the glucose-induced GSK3β activation has negative osteogenic effects on BMSCs by suppressing β-catenin/Tcf7/Ccn4 signaling axis. Inhibition of GSK3β by specific concentrations of LiCl could reverse the impaired osteogenesis of BMSCs and increase expression of β-catenin, Tcf7 and Ccn4. Our research indicated that abnormal activation of GSK3β plays a role in diabetic osteoporosis and might be a potential target to treat diabetic osteoporosis.

The effect of vascular complications of diabetes mellitus on human umbilical cord tissue and the number of Wharton Jelly's mesenchymal stem cells

The current study investigated the change in umbilical cord tissue and the number of markers of Wharton's jelly mesenchymal stem cells (WJ-MSC) in pregnant women with gestational diabetes (GDM), with chronic diabetes who developed nephropathy as vascular complication (VC-PGDM), and healthy pregnant women as the control. The umbilical cords (UC) were investigated by the histomorphological method and the number of WJ-MSC were detected by flow-cytometry using the CD90, CD44, CD105, and CD73 markers in Wharton's jelly (WJ) isolated from fresh umbilical cords. The number of positive cells for CD 90, CD44, CD105, and CD73 were found to be elevated in the GDM group, whereas it was significantly diminished in the VC-PGDM group (p = 0.001, p = 0.001, p = 0.001, and p = 0.001). The only histopathological sign in the GDM group were an increased number of pores in the Wharton jelly. Artery wall thickness/cord diamater ratio was increased, which indicates an increase of the artery wall thickness in the VC- PGDM group (p = 0.039 and p = 0.048). The increase in umbilical cord diameter and number of Wharton jelly mesenchymal stem cells in babies of gestational diabetic mothers was considered as an effect of macrosomia seen in babies of mothers with gestational diabetes. Vasculopathy, a long-term complication of diabetes, is known to affect all tissues by causing marked lower perfusion and hypoxia, as well as a decrease in the MSC number in our study.

Tissue-specific angiogenic and invasive properties of human neonatal thymus and bone MSCs: Role of SLIT3-ROBO1

Although mesenchymal stem/stromal cells (MSCs) are being explored in numerous clinical trials as proangiogenic and proregenerative agents, the influence of tissue origin on the therapeutic qualities of these cells is poorly understood. Complicating the functional comparison of different types of MSCs are the confounding effects of donor age, genetic background, and health status of the donor. Leveraging a clinical setting where MSCs can be simultaneously isolated from discarded but healthy bone and thymus tissues from the same neonatal patients, thereby controlling for these confounding factors, we performed an in vitro and in vivo paired comparison of these cells. We found that both neonatal thymus (nt)MSCs and neonatal bone (nb)MSCs expressed different pericytic surface marker profiles. Further, ntMSCs were more potent in promoting angiogenesis in vitro and in vivo and they were also more motile and efficient at invading ECM in vitro. These functional differences were in part mediated by an increased ntMSC expression of SLIT3, a factor known to activate endothelial cells. Further, we discovered that SLIT3 stimulated MSC motility and fibrin gel invasion via ROBO1 in an autocrine fashion. Consistent with our findings in human MSCs, we found that SLIT3 and ROBO1 were expressed in the perivascular cells of the neonatal murine thymus gland and that global SLIT3 or ROBO1 deficiency resulted in decreased neonatal murine thymus gland vascular density. In conclusion, ntMSCs possess increased proangiogenic and invasive behaviors, which are in part mediated by the paracrine and autocrine effects of SLIT3.

Inhibition of GDF11 could promote bone healing in the tooth extraction socket and facilitate mesenchymal stem cell osteogenic differentiation in T2DM pigs

BACKGROUND

Growth differentiation factor 11 (GDF11) might be a key factor responsible for the weakening of mesenchymal stem cell (MSC) osteogenic differentiation in tooth extraction sockets in patients with type 2 diabetes mellitus (T2DM). This study aimed to confirm that inhibition of GDF11 could promote bone healing in tooth extraction sockets and facilitate MSC osteogenic differentiation under T2DM conditions.

METHODS

Three streptozotocin-induced T2DM pig models and two control pig models were established. The T2DM pigs were treated with an intrasocket injection of GDF11 inhibitor in the left mandible, whereas the right side was maintained for natural healing. The postextraction socket healing of the T2DM pigs was compared with that of nondiabetic controls. Healing was quantitatively verified by microcomputed tomography, and the GDF11 expression level was detected. MSCs from T2DM pig sockets were cultured and treated with a GDF11 inhibitor. The osteogenic differentiation ability of MSCs was also compared among groups.

RESULTS

The expression of GDF11 in the tooth extraction sockets from T2DM pigs increased significantly post extraction. Bone healing was promoted by periodic injection of the GDF11 inhibitor into the extraction sockets of T2DM pigs. Furthermore, the osteogenic differentiation ability of T2DM-MSCs was improved in pigs treated with the GDF11 inhibitor.

CONCLUSIONS

GDF11 inhibition could promote bone healing in the tooth extraction socket and facilitate MSC osteogenic differentiation under T2DM conditions. GDF11 could be a potential therapeutic target for undesirable alveolar bone healing in T2DM patients.

Platelet-rich plasma counteracts detrimental effect of high-glucose concentrations on mesenchymal stem cells from Bichat fat pad

Diabetic patients display increased risk of periodontitis and failure in bone augmentation procedures. Mesenchymal stem cells (MSCs) and platelet-rich plasma (PRP) represent a relevant advantage in tissue repair process and regenerative medicine. We isolated MSCs from Bichat's buccal fat pad (BFP) and measured the effects of glucose and PRP on cell number and osteogenic differentiation potential. Cells were cultured in the presence of 5.5-mM glucose (low glucose [LG]) or 25-mM glucose (high glucose [HG]). BFP-MSC number was significantly lower when cells were cultured in HG compared with those in LG. Following osteogenic differentiation procedures, calcium accumulation, alkaline phosphatase activity, and expression of osteogenic markers were significantly lower in HG compared with LG. Exposure of BFP-MSC to PRP significantly increased cell number and osteogenic differentiation potential, reaching comparable levels in LG and in HG. Thus, high-glucose concentrations impair BFP-MSC growth and osteogenic differentiation. However, these detrimental effects are largely counteracted by PRP.

Model for Studying the Effects of Chronic Metabolic Disease on Endogenous Bone Marrow Stem Cell Populations

Disease-associated impairment/dysfunction of stem cell populations is prominent in chronic metabolic and inflammatory diseases, such as type 2 diabetes mellitus (DM) where the multifunctional properties (viability, proliferation, paracrine secretion, multilineage differentiation) of bone marrow resident mesenchymal stem cells (MSCs) can be affected. The growth and viability impairments make it difficult to study the underlying molecular mechanisms related to the dysfunction of these cells in vitro. We have consequently optimized the isolation and culture conditions for impaired/dysfunctional bone marrow MSCs from B6.Cg-Lep^ob/J obese prediabetic mice. The method described here permits ex vivo investigations into disease-associated functional impairments and the dysregulated molecular mechanisms in these primary MSCs through direct comparisons with their healthy wild-type C57BL6/J control mouse counterparts.

Cellular Senescence as the Pathogenic Hub of Diabetes-Related Wound Chronicity

Diabetes is constantly increasing at a rate that outpaces genetic variation and approaches to pandemic magnitude. Skin cells physiology and the cutaneous healing response are progressively undermined in diabetes which predisposes to lower limb ulceration, recidivism, and subsequent lower extremities amputation as a frightened complication. The molecular operators whereby diabetes reduces tissues resilience and hampers the repair mechanisms remain elusive. We have accrued the notion that diabetic environment embraces preconditioning factors that definitively propel premature cellular senescence, and that ulcer cells senescence impair the healing response. Hyperglycemia/oxidative stress/mitochondrial and DNA damage may act as major drivers sculpturing the senescent phenotype. We review here historical and recent evidences that substantiate the hypothesis that diabetic foot ulcers healing trajectory, is definitively impinged by a self-expanding and self-perpetuative senescent cells society that drives wound chronicity. This society may be fostered by a diabetic archetypal secretome that induces replicative senescence in dermal fibroblasts, endothelial cells, and keratinocytes. Mesenchymal stem cells are also susceptible to major diabetic senescence drivers, which accounts for the inability of these cells to appropriately assist in diabetics wound healing. Thus, the use of autologous stem cells has not translated in significant clinical outcomes. Novel and multifaceted therapeutic approaches are required to pharmacologically mitigate the diabetic cellular senescence operators and reduce the secondary multi-organs complications. The senescent cells society and its adjunctive secretome could be an ideal local target to manipulate diabetic ulcers and prevent wound chronification and acute recidivism. This futuristic goal demands harnessing the diabetic wound chronicity epigenomic signature.

Autologous adipose-derived stem cells for the treatment of complex cryptoglandular perianal fistula: A randomized clinical trial with long-term follow-up

The aim of this clinical trial (ID Number NCT01803347) was to determine the safety and efficacy of autologous adipose‐derived stem cells (ASCs) for treatment of cryptoglandular fistula. This research was conducted following an analysis of the mistakes of a same previous phase III clinical trial. We designed a multicenter, randomized, single‐blind clinical trial, recruiting 57 patients. Forty‐four patients were categorized as belonging to the intent‐to‐treat group. Of these, 23 patients received 100 million ASCs plus intralesional fibrin glue (group A) and 21 received intralesional fibrin glue (group B), both after a deeper curettage of tracks and closure of internal openings. Fistula healing was defined as complete re‐epithelialization of external openings. Those patients in whom the fistula had not healed after 16 weeks were eligible for retreatment. Patients were evaluated at 1, 4, 16, 36, and 52 weeks and 2 years after treatment. Results were assessed by an evaluator blinded to the type of treatment. After 16 weeks, the healing rate was 30.4% in group A and 42.8% in group B, rising to 55.0% and 63.1%, respectively, at 52 weeks. At the end of the study (2 years after treatment), the healing rate remained at 50.0% in group A and had reduced to 26.3% in group B. The safety of the cellular treatment was confirmed and no impact on fecal continence was detected. The main conclusion was that autologous ASCs for the treatment of cryptoglandular perianal fistula is safe and can favor long‐term and sustained fistula healing.

Stem cell-derived extracellular vesicles for renal repair: do cardiovascular comorbidities matter?

Extracellular vesicle (EV)-based regenerative therapy has shown promising results in preclinical models of renal disease and might be useful for patients with several forms of chronic kidney disease. However, individuals with chronic kidney disease often present with comorbidities, including obesity, hypertension, diabetes, or even metabolic syndrome, which may alter the endogenous characteristics and impair the reparative capacity of stem cells and their daughter EVs. This brief review summarizes evidence of alterations in the morphology, cargo, and function of mesenchymal stem cells and mesenchymal stem cell-derived EVs in the face of cardiovascular disease. We further discuss the important ramifications for their use in patients with kidney disease.

2,3,7,8-Tetrachlorodibenzo-p-dioxin-induced aryl hydrocarbon receptor activation enhanced the suppressive function of mesenchymal stem cells against splenocyte proliferation

The immunosuppressive function of mesenchymal stem cells (MSCs) is well known. Aryl hydrocarbon receptor (AhR), a transcription factor of the bHLH/PAS family, is widely expressed in several cells and is involved in various physiological and pathological processes. Previously, we found that the expression of AhR was downregulated in MSCs isolated from mice with neutrophilic asthma and that the activation of AhR enhanced the function of MSCs to alleviate neutrophilic asthma. We hypothesized that AhR activation enhanced MSCs for their immunosuppressive function. We aimed to investigate whether AhR activation can augment the suppressive function of MSCs against splenocyte proliferation. We co-cultured MSCs or AhR-activated MSCs with splenocytes at different ratios. The results showed that AhR activation in MSCs upregulated the expression of inducible nitric oxide (iNOS), which promoted the production of nitric oxide (NO), thus enhancing the inhibitory effect on splenocyte proliferation. The NO donor S-nitroso-N-acetylpenicillamine also inhibited the proliferation of splenocytes, and the iNOS inhibitor N(G)-nitro L-arginine methyl ester and NO scavenger 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide partially reversed the immunosuppressive function. Our study indicates that the AhR activation of MSCs might have an important role in the regulation of splenocyte proliferation and might serve as a potential strategy for treating immune-related diseases.

Mesenchymal Stem Cells in Homeostasis and Systemic Diseases: Hypothesis, Evidences, and Therapeutic Opportunities

Mesenchymal stem cells (MSCs) are present in all organs and tissues, playing a well-known function in tissue regeneration. However, there is also evidence indicating a broader role of MSCs in tissue homeostasis. In vivo studies have shown MSC paracrine mechanisms displaying proliferative, immunoregulatory, anti-oxidative, or angiogenic activity. In addition, recent studies also demonstrate that depletion and/or dysfunction of MSCs are associated with several systemic diseases, such as lupus, diabetes, psoriasis, and rheumatoid arthritis, as well as with aging and frailty syndrome. In this review, we hypothesize about the role of MSCs as keepers of tissue homeostasis as well as modulators in a variety of inflammatory and degenerative systemic diseases. This scenario opens the possibility for the use of secretome-derived products from MSCs as new therapeutic agents in order to restore tissue homeostasis, instead of the classical paradigm "one disease, one drug".