Mesothelial Stem Cells and Stromal Vascular Fraction for Skin Rejuvenation

Advances in the Applications of Extracellular Vesicle for the Treatment of Skin Photoaging: A Comprehensive Review

Skin photoaging is a complex biological process characterized by the accumulation of oxidative damage and structural changes in the skin, resulting from chronic exposure to ultraviolet (UV) radiation. Despite the growing demand for effective treatments, current therapeutic options for skin photoaging remain limited. However, emerging research has highlighted the potential of extracellular vesicles (EVs), including exosomes, micro-vesicles, apoptotic bodies and liposomes, as promising therapeutic agents in skin rejuvenation. EVs are involved in intercellular communication and can deliver bioactive molecules, including proteins, nucleic acids, and lipids, to recipient cells, thereby influencing various cellular processes. This comprehensive review aims to summarize the current research progress in the application of EVs for the treatment of skin photoaging, including their isolation and characterization methods, roles in skin homeostasis, therapeutic potential and clinical applications for skin photoaging. Additionally, challenges and future directions in EVs-based therapies for skin rejuvenation are discussed.

Metformin promotes angiogenesis by enhancing VEGFa secretion by adipose-derived stem cells via the autophagy pathway

Human adipose tissue-derived stem cell (ADSC) derivatives are cell-free, with low immunogenicity and no potential tumourigenicity, making them ideal for aiding wound healing. However, variable quality has impeded their clinical application. Metformin (MET) is a 5' adenosine monophosphate-activated protein kinase activator associated with autophagic activation. In this study, we assessed the potential applicability and underlying mechanisms of MET-treated ADSC derivatives in enhancing angiogenesis. We employed various scientific techniques to evaluate the influence of MET on ADSC, assess angiogenesis and autophagy in MET-treated ADSC in vitro, and examine whether MET-treated ADSC increase angiogenesis. We found that low MET concentrations exerted no appreciable effect on ADSC proliferation. However, MET was observed to enhance the angiogenic capacity and autophagy of ADSC. MET-induced autophagy was associated with increased vascular endothelial growth factor A production and release, which contributed to promoting the therapeutic efficacy of ADSC. In vivo experiments confirmed that in contrast to untreated ADSC, MET-treated ADSC promoted angiogenesis. Our findings thus indicate that the application of MET-treated ADSC would be an effective approach to accelerate wound healing by promoting angiogenesis at wound sites.

Small extracellular vesicles derived from human adipose-derived stem cells regulate energetic metabolism through the activation of YAP/TAZ pathway facilitating angiogenesis

Recent studies have found small extracellular vesicles (sEVs) that are secreted from human adipose tissue-derived stem cells (hADSCs-sEVs) and contribute to angiogenesis. Glycolysis, the primary energetic pathway of vascular endothelial cells, plays a key role in the process of angiogenesis. However, hADSCs-sEVs' effects on energy metabolism within endothelial cells remain unclear. In our study, we found that hADSCs-sEVs restored glycolytic metabolism suppressed by 3-(pyridinyl)-1-(4-pyridinyl)-2-propen-1-one(3PO), a unique glycolytic inhibitor increasing the extracellular acidification rate (ECAR), oxygen consumption rate (OCR), glycolytic gene expression as well as pyruvate, lactate, and ATP production in HUVEC cells. In contrast, hADSCs-sEVs decreased PDH-E1α expression and acetyl-CoA production. The above results indicate that hADSCs-sEVs promote HUVEC angiogenesis via enhancing glycolysis and suppressing mitochondrial oxidative phosphorylation. Furthermore, we found that the YAP/TAZ pathway may play a key role in the effects hADSCs-sEVs have on HUVECs, thus, providing a promising approach for pro-angiogenesis-related regeneration.

The Therapeutic Application of Stem Cells and Their Derived Exosomes in the Treatment of Radiation-Induced Skin Injury

Radiation-induced skin injury (RISI) is a serious concern for nuclear accidents and cancer radiotherapy, which seriously affects the quality of life of patients. This injury differs from traditional wounds due to impaired healing and the propensity to recurrence and is divided into acute and chronic phases on the basis of the injury time. Unfortunately, there are few effective therapies for preventing or mitigating this injury. Over the last few decades, various studies have focused on the effects of stem cell-based therapies to address the tissue repair and regeneration of irradiated skin. These stem cells modulate inflammation and instigate tissue repair by differentiating into specific kinds of cells or releasing paracrine factors. Stem cell-based therapies, including bone marrow-derived stem cells (BMSCs), adipose-derived stem cells (ADSCs) and stromal vascular fraction (SVF), have been reported to facilitate wound healing after radiation exposure. Moreover, stem cell-derived exosomes have recently been suggested as an effective and cell-free approach to support skin regeneration, circumventing the concerns respecting direct application of stem cells. Based on the literature on stem cell-based therapies for radiation-induced skin injury, we summarize the characteristics of different stem cells and describe their latest animal and clinical applications, as well as potential mechanisms. The promise of stem-cell based therapies against radiation-induced skin injury contribute to our response to nuclear events and smooth progress of cancer radiotherapy.

The Therapeutic Role of ADSC-EVs in Skin Regeneration

Large skin defects caused by burns, unhealing chronic wounds, and trauma, are still an intractable problem for clinicians and researchers. Ideal skin regeneration includes several intricate and dynamic stages of wound repair and regeneration of skin physiological function. Adipose-derived stem cells (ADSCs), a type of mesenchymal stem cells (MSCs) with abundant resources and micro-invasive extraction protocols, have been reported to participate in each stage of promoting skin regeneration via paracrine effects. As essential products secreted by ADSCs, extracellular vesicles (EVs) derived from ADSCs (ADSC-EVs) inherit such therapeutic potential. However, ADSC-EVs showed much more clinical superiorities than parental cells. ADSC-EVs carry various mRNAs, non-coding RNAs, proteins, and lipids to regulate the activities of recipient cells and eventually accelerate skin regeneration. The beneficial role of ADSCs in wound repair has been widely accepted, while a deep comprehension of the mechanisms of ADSC-EVs in skin regeneration remains unclear. In this review, we provided a basic profile of ADSC-EVs. Moreover, we summarized the latest mechanisms of ADSC-EVs on skin regeneration from the aspects of inflammation, angiogenesis, cell proliferation, extracellular matrix (ECM) remodeling, autophagy, and oxidative stress. Hair follicle regeneration and skin barrier repair stimulated by ADSC-EVs were also reviewed. The challenges and prospects of ADSC-EVs-based therapies were discussed at the end of this review.

Exosomes Secreted from Adipose-Derived Stem Cells Are a Potential Treatment Agent for Immune-Mediated Alopecia

Background

Alopecia has become an exceedingly prevalent dermatological disorder. Etiologically, infection (bacterial and fungal infection), inflammation, and immune dysregulation are the main causes of immune-mediated hair loss. Treating hair loss has remained challenging as the available therapies are limited. Exosomes from adipose-derived stem cells (ADSC-Exos) have been used for treating neurodegenerative diseases and autoimmune diseases and in wound-healing treatments. However, the function and mechanism of ADSC-Exos in alopecia treatment remain unclear. This study is aimed at investigating the effects of ADSC-Exos on hair growth in vitro and in vivo for potentially treating immune-mediated alopecia and further exploring the underlying mechanism.

Methods

Cell proliferation, migration, and apoptosis of dermal papilla cells (DPCs) that were treated with ADSC-Exos were detected using the cell counting kit-8 (CCK-8) assay, scratch wound-healing assay, and flow cytometry assay, respectively. A C57BL/6 hair-depilated mouse model was established in vivo; then, ADSC-Exos were subcutaneously injected alone or in combined with minoxidil. The effects of ADSC-Exos on hair growth, pathological changes, and the related mechanism were investigated by HE staining, quantitative real‐time PCR (qRT-PCR), western blotting, and RNA sequencing (RNA-seq).

Results

ADSC-Exos significantly promoted DPC proliferation and migration while also reducing apoptosis. In addition, compared with the control group, ADSC-Exos-treated mice had better hair growth, more hair follicles (HFs) and thicker dermis. RNA-seq revealed that the miR-22 and TNF-α signaling pathways were markedly downregulated in DPCs after ADSC-Exos treatment. In addition, according to qRT-PCR and western blotting results, the Wnt/β-catenin signaling pathway was activated in the skin of ADSC-Exos-treated mice.

Conclusion

ADSC-Exos therapy positively affected the promotion of hair regrowth by regulating miR-22, the Wnt/β-catenin signaling pathway, and the TNF-α signaling pathway, implying that ADSC-Exos could be a promising cell-free therapeutic strategy for immune-mediated alopecia.

Adipose-Derived Stem Cells for Facial Rejuvenation

The interest in regenerative medicine is increasing, and it is a dynamically developing branch of aesthetic surgery. Biocompatible and autologous-derived products such as platelet-rich plasma or adult mesenchymal stem cells are often used for aesthetic purposes. Their application originates from wound healing and orthopaedics. Adipose-derived stem cells are a powerful agent in skin rejuvenation. They secrete growth factors and anti-inflammatory cytokines, stimulate tissue regeneration by promoting the secretion of extracellular proteins and secrete antioxidants that neutralize free radicals. In an office procedure, without cell incubation and counting, the obtained product is stromal vascular fraction, which consists of not only stem cells but also other numerous active cells such as pericytes, preadipocytes, immune cells, and extra-cellular matrix. Adipose-derived stem cells, when injected into dermis, improved skin density and overall skin appearance, and increased skin hydration and number of capillary vessels. The main limitation of mesenchymal stem cell transfers is the survival of the graft. The final outcomes are dependent on many factors, including the age of the patient, technique of fat tissue harvesting, technique of lipoaspirate preparation, and technique of fat graft injection. It is very difficult to compare available studies because of the differences and multitude of techniques used. Fat harvesting is associated with potentially life-threatening complications, such as massive bleeding, embolism, or clots. However, most of the side effects are mild and transient: primarily hematomas, oedema, and mild pain. Mesenchymal stem cells that do not proliferate when injected into dermis promote neoangiogenesis, that is why respectful caution should be taken in the case of oncologic patients. A longer clinical observation on a higher number of participants should be performed to develop reliable indications and guidelines for transferring ADSCs.

Nanofat Cell-Mediated Anti-Aging Therapy: Evidence-Based Analysis of Efficacy and an Update of Stem Cell Facelift

BACKGROUND

Fat grafting has been extensively applied as natural filler and has been very promising in restoring volume loss. Lipografting has also been credited to reduce age-related skin changes due to the regenerative potential of adipose derived stem cells. Cell-mediated therapies in plastic surgery are rapidly evolving with growing applications. Nanofat, a bio-regenerative liquid suspension rich in stromal vascular fraction cells without viable adipocytes, has been described as an efficient cutaneous anti-aging therapy. We have published in 2013 a review entitled "stem cell facelift: between reality and fiction." Available clinical evidence at that time did not substantiate marketing and promotional claims of "stem cell facelift". The same year, the report about nanofat was published demonstrating striking clinical outcome. The current literature search is aimed at reviewing any evidence that has emerged since then regarding clinical efficacy of this modality.

METHODS

A thorough PICO tool-based comprehensive literature search of PubMed database for "the efficacy of nanofat cell-mediated anti-aging therapy" was conducted with a time frame from 2013 till present.

RESULTS

Despite apparent increasing popularity of stem cell rejuvenation, well-controlled clinical studies about this modality are surprisingly very scarce. Only seven papers published after 2013 were identified and were included in this review CONCLUSION: Though considered to be a safe procedure, and despite documented histologic improvement and striking clinical outcome in some reports, available evidence can hardly support clinical improvement of skin quality. Before cell-mediated aesthetic rejuvenation applications can be routinely undertaken, more robust evidence with well-defined primary outcome end points and objective outcome measures is required.

LEVEL OF EVIDENCE

IV.

Differences in Cytotoxicity of Lidocaine, Ropivacaine, and Bupivacaine on the Viability and Metabolic Activity of Human Adipose-Derived Mesenchymal Stem Cells

PURPOSE

We evaluated biological effects of distinct local anesthetics on human adipose-derived mesenchymal stem cells when applied to reduce periprocedural pain during mesenchymal stem cell injections.

METHODS AND MATERIALS

Metabolic activity (MTS assay), viability (Live/Dead stain), and gene expression (quantitative real-time reverse-transcriptase polymerase chain reaction) were measured in mesenchymal stem cells incubated with various concentrations of lidocaine, ropivacaine, or bupivacaine during a 12-hr time course.

RESULTS

Cell viability and metabolic activity decreased in a dose, time, and substance-specific manner after exposure to lidocaine, ropivacaine, and bupivacaine, with ropivacaine being the least cytotoxic. Cell viability decreases after brief exposure (<1.5 hrs) at clinically relevant concentrations (eg, 8 mg/ml of lidocaine, 2.5 mg/ml of ropivacaine or bupivacaine). Mesenchymal stem cells exposed to local anesthetics change their expression of mRNA biomarkers for stress response (EGR1, EGR2), proliferation (MKI67, HIST2H4A), ECM (COL1A1, COL3A1), and cell surface marker (CD105).

CONCLUSIONS

Local anesthetics are cytotoxic to clinical-grade human mesenchymal stem cells in a dose-, time-, and agent-dependent manner and change expression of ECM, proliferation, and cell surface markers. Lidocaine and bupivacaine are more cytotoxic than ropivacaine. Single-dose injections of local anesthetics may affect the biological properties of mesenchymal stem cells in vitro but may not affect the effective dose of MSCs in a clinical setting.

Therapeutic applications of adipose cell-free derivatives: a review

BACKGROUND

Adipose-derived stem cells (ADSCs) have become one of the most utilized adult stem cells due to their abundance and accessibility. Recent studies have shown that paracrine cytokines, exosomes, and other active substances are the main factors through which ADSCs exert their biological effects.

MAIN BODY

Adipose cell-free derivatives have been recently gaining attention as potential therapeutic agents for various human diseases. These derivatives include ADSC-conditioned medium (ADSC-CM), ADSC exosomes (ADSC-Exo), and cell-free adipose tissue extracts (ATEs), all of which can be conveniently carried, stored, and transported. Currently, research on ADSC-conditioned medium (ADSC-CM) and ADSC exosomes (ADSC-Exo) is surging. Moreover, cell-free adipose tissue extracts (ATEs), obtained by purely physical methods, have emerged as the focus of research in recent years.

CONCLUSION

Adipose cell-free derivatives delivery can promote cell proliferation, migration, and angiogenesis, suppress cell apoptosis, and inflammation, as well as reduce oxidative stress and immune regulation. Thus, adipose cell-free derivatives have a broad therapeutic potential in many areas, as they possess anti-skin aging properties, promote wound healing, reduce scar formation, and provide myocardial protection and neuroprotection. This article summarizes these effects and reviews research progress in the use of adipose cell-free derivatives.

The Effects of Facial Lipografting on Skin Quality: A Systematic Review

BACKGROUND

Autologous lipografting for improvement of facial skin quality was first described by Coleman in 2006. The current dogma dictates that adipose tissue-derived stromal cells that reside in the stromal vascular fraction of lipograft contribute to skin rejuvenation (e.g., increased skin elasticity), a more homogenous skin color, and softening of skin texture. Nowadays, many studies have been reported on this "skin rejuvenation" effect of autologous fat grafting. This systematic review was undertaken to assess the efficacy of autologous lipografting on skin quality.

METHODS

The MEDLINE, Embase, Cochrane Central, Web of Science, and Google Scholar databases were searched for studies evaluating the effect of autologous lipografting on facial skin quality (May 11, 2018). Outcomes of interest were skin texture, color, and elasticity in addition to histologic outcomes and number of complications.

RESULTS

Nine studies were included, with 301 patients treated in total. No meta-analysis could be performed because of heterogeneity of the metrics and outcomes. Eight studies reported increased skin elasticity; improvement in skin texture; and a more homogeneous skin color after treatment with lipografting, cellular stromal vascular fraction, or nanofat. One study reported no increased skin elasticity after lipografting. Histologic improvement was seen after lipografting and adipose tissue-derived stromal cell injections. However, in general, the level of evidence of the included studies was low. No serious complications were reported.

CONCLUSION

Autologous facial lipografting and cellular stromal vascular fraction and adipose tissue-derived stromal cell injections hardly seem to improve facial skin quality but can be considered a safe procedure.