Ex vivo antioxidant preconditioning improves the survival rate of bone marrow stem cells in the presence of wound fluid

Modification of mesenchymal stromal cells with silibinin-loaded PLGA nanoparticles improves their therapeutic efficacy for cutaneous wound repair

The use of mesenchymal stromal cells (MSCs) for treating chronic inflammatory disorders, wounds, and ischemia-reperfusion injuries has shown improved healing efficacy. However, the poor survival rate of transplanted cells due to oxidative stress in injured or inflamed tissue remains a significant concern for MSC-based therapies. In this study, we developed a new approach to protect MSCs from oxidative stress, thereby improving their survival in a wound microenvironment and enhancing their therapeutic effect. We produced PLGA nanoparticles loaded with the cytoprotective phytochemical silibinin (SBN), and used them to modify MSCs. Upon internalization, these nanoformulations released SBN, activating the Nrf2/ARE signaling pathway, resulting in threefold reduction in intracellular ROS content and improved cell survival under oxidative stress conditions. Modification of MSCs with SBN-loaded PLGA nanoparticles increased their survival upon transplantation to full-thickness cutaneous wounds and improved wound healing. This study suggests that MSC modification with cytoprotective nanoparticles could be a promising approach for improving wound healing.

Priming of adipose-derived stem cells with curcumin prior to cryopreservation preserves their functional potency: Towards an 'Off-the-shelf' therapy for burns

Stem cells-based treatment for burn wounds require frozen cells as an off-the-shelf therapy; however, cryopreservation-induced oxidative stress resulted in post-thaw cell death or loss of cell functions, thus arrested their clinical practicality. Although antioxidant priming to stem cells increase their resistant to oxidative stress, but this strategy is still unexplored on cryopreserved cells. Herein, we investigated whether curcumin priming before cryopreservation could preserve the therapeutic potency of thawed stem cells. For this, unprimed and curcumin-primed adipose-derived stem cells (ASCs) were cryopreserved for one month. Post-thawing, cells were assessed for viability by trypan blue assay; metabolic activity by MTT assay; senescence by senescence-associated (SA)-β-galactosidase activity staining assay; migration by scratch healing assay and; mRNA expression by real-time PCR. Subsequently, the healing potential was examined by injecting cells around the wound periphery of acidic burn in rats. Post-healing, skin architecture was histologically examined. Results demonstrated that, curcumin-primed frozen cells (Cryo/Cur-ASCs) showed better post-thaw viability, metabolic activity, migration ability and lower percent of senescence comparative to unprimed frozen cells (Cryo/ASCs). Curcumin priming alleviated the oxidative damage by activating the ROS-reducing cellular antioxidant system as shown by the evident increase in GSH levels and upregulated mRNA expression of glutathione peroxidase (GPx), superoxide dismutases (SOD1, SOD2), and catalase (CAT). Further, invivo findings revealed that Cryo/Cur-ASCs-treated wounds exhibited earlier wound closure with an improved architecture comparative to Cryo/ASCs and depicted healing capacity almost similar to Fresh/ASCs. Our findings suggested that curcumin priming could be effective to alleviate the cryo-induced oxidative stress in post-thawed cells.

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.

Improvement of ECM-based bioroot regeneration via N-acetylcysteine-induced antioxidative effects

BACKGROUND

The low survival rate or dysfunction of extracellular matrix (ECM)-based engineered organs caused by the adverse effects of unfavourable local microenvironments on seed cell viability and stemness, especially the effects of excessive reactive oxygen species (ROS), prompted us to examine the importance of controlling oxidative damage for tissue transplantation and regeneration. We sought to improve the tolerance of seed cells to the transplant microenvironment via antioxidant pathways, thus promoting transplant efficiency and achieving better tissue regeneration.

METHODS

We improved the antioxidative properties of ECM-based bioroots with higher glutathione contents in dental follicle stem cells (DFCs) by pretreating cells or loading scaffolds with the antioxidant NAC. Additionally, we developed an in situ rat alveolar fossa implantation model to evaluate the long-term therapeutic effects of NAC in bioroot transplantation.

RESULTS

The results showed that NAC decreased H₂O₂-induced cellular damage and maintained the differentiation potential of DFCs. The transplantation experiments further verified that NAC protected the biological properties of DFCs by repressing replacement resorption or ankylosis, thus facilitating bioroot regeneration.

CONCLUSIONS

The following findings suggest that NAC could significantly protect stem cell viability and stemness during oxidative stress and exert better and prolonged effects in bioroot intragrafts.

Targeting Stem Cells in Chronic Inflammatory Diseases

Mesenchymal stem cell (MSC) dysfunction is a serious complication in ageing and age-related inflammatory diseases such as type 2 diabetes mellitus. Inflammation and oxidative stress-induced cellular senescence alter the immunomodulatory ability of MSCs and hamper their pro-regenerative function, which in turn leads to an increase in disease severity, maladaptive tissue damage and the development of comorbidities. Targeting stem/progenitor cells to restore their function and/or protect them against impairment could thus improve healing outcomes and significantly enhance the quality of life for diabetic patients. This review discusses the dysregulation of MSCs' immunomodulatory capacity in the context of diabetes mellitus and focuses on intervention strategies aimed at MSC rejuvenation. Research pertaining to the potential therapeutic use of either pharmacological agents (NFкB antagonists), natural products (phytomedicine) or biological agents (exosomes, probiotics) to improve MSC function is discussed and an overview of the most pertinent methodological considerations given. Based on in vitro studies, numerous anti-inflammatory agents, antioxidants and biological agents show tremendous potential to revitalise MSCs. An integrated systems approach and a thorough understanding of complete disease pathology are however required to identify feasible candidates for in vivo targeting of MSCs.

Novel insights for improving the therapeutic safety and efficiency of mesenchymal stromal cells

Mesenchymal stromal cells (MSCs) have attracted great interest in the field of regenerative medicine. They can home to damaged tissue, where they can exert pro-regenerative and anti-inflammatory properties. These therapeutic effects involve the secretion of growth factors, cytokines, and chemokines. Moreover, the functions of MSCs could be mediated by extracellular vesicles (EVs) that shuttle various signaling messengers. Although preclinical studies and clinical trials have demonstrated promising therapeutic results, the efficiency and the safety of MSCs need to be improved. After transplantation, MSCs face harsh environmental conditions, which likely dampen their therapeutic efficacy. A possible strategy aiming to improve the survival and therapeutic functions of MSCs needs to be developed. The preconditioning of MSCs ex vivo would strength their capacities by preparing them to survive and to better function in this hostile environment. In this review, we will discuss several preconditioning approaches that may improve the therapeutic capacity of MSCs. As stated above, EVs can recapitulate the beneficial effects of MSCs and may help avoid many risks associated with cell transplantation. As a result, this novel type of cell-free therapy may be safer and more efficient than the whole cell product. We will, therefore, also discuss current knowledge regarding the therapeutic properties of MSC-derived EVs.