The potential use of stem cells derived from human amniotic fluid in renal diseases

The Angiogenic Repertoire of Stem Cell Extracellular Vesicles: Demystifying the Molecular Underpinnings for Wound Healing Applications

Stem cells-derived extracellular vesicles (SC-EVs) have emerged as promising therapeutic agents for wound repair, recapitulating the biological effects of parent cells while mitigating immunogenic and tumorigenic risks. These EVs orchestrate wound healing processes, notably through modulating angiogenesis-a critical event in tissue revascularization and regeneration. This study provides a comprehensive overview of the multifaceted mechanisms underpinning the pro-angiogenic capacity of EVs from various stem cell sources within the wound microenvironment. By elucidating the molecular intricacies governing their angiogenic prowess, we aim to unravel the mechanistic repertoire underlying their remarkable potential to accelerate wound healing. Additionally, methods to enhance the angiogenic effects of SC-EVs, current limitations, and future perspectives are highlighted, emphasizing the significant potential of this rapidly advancing field in revolutionizing wound healing strategies.

Stem cell-derived exosomes: emerging therapeutic opportunities for wound healing

Wound healing is a dynamic and highly sequential process involving a series of overlapping spatial and temporal phases, including hemostasis, inflammation, proliferation, and tissue remodeling. Mesenchymal stem cells (MSCs) are multipotent stem cells with self-renewal, multidirectional differentiation potential, and paracrine regulation. Exosomes are subcellular vesicular components 30-150 nm in size and are novel carriers of intercellular communication in regulating the biological behaviors of skin cells. Compared to MSCs, MSC-derived exosomes (MSC-exos) possess lower immunogenicity, easy storage, and highly effective biological activity. MSC-exos, mainly derived from adipose-derived stem cells (ADSCs), bone marrow-derived MSCs (BMSCs), human umbilical cord MSCs (hUC-MSCs), and other stem cell types, play a role in shaping the activity of fibroblasts, keratinocytes, immune cells, and endothelial cells in diabetic wounds, inflammatory wound repair, and even wound-related keloid formation. Therefore, this study focuses on the specific roles and mechanisms of different MSC-exos in wound healing, as well as the current limitations and various perspectives. Deciphering the biological properties of MSC-exos is crucial to providing a promising cell-free therapeutic tool for wound healing and cutaneous regeneration.

Synergic Renoprotective Effects of Combined ASC Therapy with RAAS Blockade in Experimental Advanced CKD

Global prevalence of chronic kidney disease (CKD) has increased considerably in the recent decades. Overactivity of the renin-angiotensin-aldosterone system (RAAS), associated to renal inflammation and fibrosis, contributes to its evolution. The treatments currently employed to control CKD progression are limited and mainly based on the pharmacological inhibition of RAAS, associated with diuretics and immunosuppressive drugs. However, this conservative management promotes only partial deceleration of CKD evolution and does not completely avoid the progression of the disease and the loss of renal function, which motivates the medical and scientific community to investigate new therapeutic approaches to detain renal inflammation/fibrosis and CKD progression. Recent studies have shown the application of mesenchymal stem cells (mSC) to exert beneficial effects on the renal tissue of animals submitted to experimental models of CKD. In this context, the aim of the present study was to evaluate the effects of subcapsular application of adipose tissue-derived mSC (ASC) in rats submitted to the 5/6 renal ablation model, 15 days after the establishment of CKD, when the nephropathy was already severe. We also verify whether ASC associated to Losartan would promote greater renoprotection when compared to the respective monotherapies. Animals were followed until 30 days of CKD, when body weight, systolic blood pressure, biochemical, histological, immunohistochemical, and gene expression analysis were performed. The combination of ASC and Losartan was more effective than Losartan monotherapy in reducing systolic blood pressure and glomerulosclerosis and also promoted the complete normalization of proteinuria and albuminuria, a significant reduction in renal interstitial macrophage infiltration and downregulation of renal IL-6 gene expression. The beneficial effects of ACS are possibly due to the immunomodulatory and anti-inflammatory role of factors secreted by these cells, modulating the local immune response. Although studies are still required, our results demonstrated that a subcapsular inoculation of ASC, associated with the administration of Losartan, exerted additional renoprotective effect in rats submitted to a severe model of established CKD, when compared to Losartan monotherapy, thus suggesting ASC may be a potential adjuvant to RAAS-blockade therapy currently employed in the conservative management of CKD.

Enhanced efficiency in isolation and expansion of hAMSCs via dual enzyme digestion and micro-carrier

A two-stage method of obtaining viable human amniotic stem cells (hAMSCs) in large-scale is described. First, human amniotic stem cells are isolated via dual enzyme (collagenase II and DNAase I) digestion. Next, relying on a culture of the cells from porous chitosan-based microspheres in vitro, high purity hAMSCs are obtained in large-scale. Dual enzymatic (collagenase II and DNase I) digestion provides a primary cell culture and first subculture with a lower contamination rate, higher purity and a larger number of isolated cells. The obtained hAMSCs were seeded onto chitosan microspheres (CM), gelatin-chitosan microspheres (GCM) and collagen-chitosan microspheres (CCM) to produce large numbers of hAMSCs for clinical trials. Growth activity measurement and differentiation essays of hAMSCs were realized. Within 2 weeks of culturing, GCMs achieved over 1.28 ± 0.06 × 107 hAMSCs whereas CCMs and CMs achieved 7.86 ± 0.11 × 106 and 1.98 ± 0.86 × 106 respectively within this time. In conclusion, hAMSCs showed excellent attachment and viability on GCM-chitosan microspheres, matching the hAMSCs' normal culture medium. Therefore, dual enzyme (collagenase II and DNAase I) digestion may be a more useful isolation process and culture of hAMSCs on porous GCM in vitro as an ideal environment for the large-scale expansion of highly functional hAMSCs for eventual use in stem cell-based therapy.

Reno-protection of Urine-derived Stem Cells in A Chronic Kidney Disease Rat Model Induced by Renal Ischemia and Nephrotoxicity

Purpose: Drug-induced nephrotoxicity can occur in patients with pre-existing renal dysfunction or renal ischemia, potentially leading to chronic kidney disease (CKD) and end-stage renal disease (ESRD). Prompt treatment of CKD and the related side effects is critical in preventing progression to ESRD. The goal of this study was to demonstrate the therapeutic potential of urine-derived stem cells (USC) to treat chronic kidney disease-induced by nephrotoxic drugs and renal ischemia.

Materials and methods: Human USC were collected, expanded and characterized by flow cytometry. A CKD model was induced by creating an ischemia-reperfusion injury and gentamicin administration. Twenty-eight adult immunodeficient rats were divided into three groups: PBS-treated group (n=9), USC-treated group (n=9), and sham group with age-matched control animals (n=10). Cell suspension of USC (5 x 10⁶ / 100µl / kidney) or PBS was injected bilaterally into the renal parenchyma 9 weeks after CKD model creation. Renal function was evaluated by collection blood and urine samples to measure serum creatinine and glomerulus filtration rate. The kidneys were harvested 12 weeks after cell injection. Histologically, the extent of glomerulosclerosis and tubular atrophy, the amount of collagen deposition, interstitial fibrosis, inflammatory monocyte infiltration, and expression of transforming growth factor beta 1 (TGF-ß1), and superoxide dismutase 1 (SOD-1) were examined.

Results: USC expressed renal parietal epithelial cells (CD24, CD29 and CD44). Renal function, measured by GFR and serum Cr in USC-treated group were significantly improved compared to PBS-treated animals (p<0.05). The degree of glomerular sclerosis and atrophic renal tubules, the amount of fibrosis, and monocyte infiltration significantly decreased in USC-treated group compared to the PBS group (p<0.05). The level of TGF-ß1 expression in renal tissues was also significantly lower in the PBS group, while the level of SOD-1 expression was significantly elevated in the USC group, compared to PBS group (p<0.05).

Conclusions: The present study demonstrates the nephron-protective effect of USC on renal function via anti-inflammatory, anti-oxidative stress, and anti-fibrotic activity in a dual-injury CKD rat model. This provides an alternative treatment for CKD in certain clinical situations, such as instances where CKD is due to drug-induced nephrotoxicity and renal ischemia.

Human mid-trimester amniotic fluid (stem) cells lack expression of the pluripotency marker OCT4A

Expression of OCT4A is one of the hallmarks of pluripotency, defined as a stem cell's ability to differentiate into all the lineages of the three germ layers. Despite being defined as non-tumorigenic cells with high translational potential, human mid-trimester amniotic fluid stem cells (hAFSCs) are often described as sharing features with embryonic stem cells, including the expression of OCT4A, which could hinder their clinical potential. To clarify the OCT4A status of hAFSCs, we first undertook a systematic review of the literature. We then performed extensive gene and protein expression analyses to discover that neither frozen, nor fresh hAFSCs cultivated in multipotent stem cell culture conditions expressed OCT4A, and that the OCT4A positive results from the literature are likely to be attributed to the expression of pseudogenes or other OCT4 variants. To address this issue, we provide a robust protocol for the assessment of OCT4A in other stem cells.

Renogenic characterization and in vitro differentiation of rat amniotic fluid stem cells into renal proximal tubular- and juxtaglomerular-like cells

The aim of the present study was to investigate the renogenic characteristics of amniotic fluid stem cells (AFSCs) and to evaluate their in vitro differentiation potential into renal proximal tubular-like cells and juxtaglomerular-like cells. We culture expanded AFSCs derived from rat amniotic fluid. The AFSCs grew as adherent spindle-shaped cells and expressed mesenchymal markers CD73, CD90, and CD105 as well as renal progenitor markers WT1, PAX2, SIX2, SALL1, and CITED1. AFSCs exhibited an in vitro differentiation potential into renal proximal tubular epithelial-like cells, as shown by the upregulation of expression of proximal tubular cell-specific genes like AQP1, CD13, PEPT1, GLUT5, OAT1, and OCT1. AFSCs could also be differentiated into juxtaglomerular-like cells as demonstrated by the expression of renin and α-SMA. The AFSCs also expressed pluripotency markers OCT4, NANOG, and SOX2 and could be induced into embryoid bodies with differentiation into all the three germ layers, highlighting the pluripotent nature of these cells. Our results show that amniotic fluid contains a population of primitive stem cells that express renal-progenitor markers and also possess the propensity to differentiate into two renal lineage cell types and, thus, may have a therapeutic potential in renal regenerative medicine.

Tissue-Engineering Approaches to Restore Kidney Function

Kidney transplantation for the treatment of chronic kidney disease has established outcome and quality of life. However, its implementation is severely limited by a chronic shortage of donor organs; consequently, most candidates remain on dialysis and on the waiting list while accruing further morbidity and mortality. Furthermore, those patients that do receive kidney transplants are committed to a life-long regimen of immunosuppressive drugs that also carry significant adverse risk profiles. The disciplines of tissue engineering and regenerative medicine have the potential to produce alternative therapies which circumvent the obstacles posed by organ shortage and immunorejection. This review paper describes some of the most promising tissue-engineering solutions currently under investigation for the treatment of acute and chronic kidney diseases. The various stem cell therapies, whole embryo transplantation, and bioengineering with ECM scaffolds are outlined and summarized.

Protective effects of human amniotic fluid stem cells in a model of aorta allograft vasculopathy in rats

BACKGROUND

Chronic allograft vasculopathy (CAV) is an important cause of graft loss. Considering the immune inflammatory events involved in the development of CAV, therapeutic approaches to target this process are of relevance. Human amniotic fluid-derived stem cells (hAFSCs), a class of fetal, pluripotent stem cells with intermediate characteristics between embryonic and adult stem cells, display immunomodulatory properties. hAFSCs express mesenchymal and embryonic markers, show high proliferation rates; however, they do not induce tumor formation, and their use does not raise ethical issues. Thus, we sought to investigate the effect of hAFSC on CAV in a model of aorta transplantation.

METHODS

Orthotopic aorta transplantation was performed using Fisher (F344) rats as donors and Lewis rats as recipients. Rats were divided into three groups: syngeneic (SYNG), untreated F344 receiving aorta from F344 (n = 8); allogeneic (ALLO), Lewis rats receiving allogeneic aorta from F344 (n = 8); and ALLO + hAFSC, ALLO rats treated with hAFSC (10(6) cells; n = 8). Histological analysis and immunohistochemistry were performed 30 days posttransplantation.

RESULTS

The ALLO group developed a robust aortic neointimal formation (208.7 ± 25.4 μm) accompanied by a significant high number of ED1+ (4845 ± 841 cells/mm2) and CD43+ cells (4064 ± 563 cells/mm2), and enhanced expression of α-smooth muscle actin in the neointima (25 ± 6%). Treatment with hAFSC diminished neointimal thickness (180.7 ± 23.7 μm) and induced a significant decrease of ED1+ (1100 ± 276 cells/mm2), CD43+ cells (1080 ± 309 cells/μm2), and α-smooth muscle actin expression 8 ± 3% in the neointima.

CONCLUSIONS

These preliminary results showed that hAFSC suppressed inflammation and myofibroblast migration to the intima, which may contribute to ameliorate vascular changes in CAV.