The effects of human keratinocyte coculture on human adipose-derived stem cells

MCPIP-1 knockdown enhances endothelial colony-forming cell angiogenesis via the TFRC/AKT/mTOR signaling pathway in the ischemic penumbra of MCAO mice

Cerebral ischemia is a serious disease characterized by brain tissue ischemia and hypoxic necrosis caused by the blockage of blood vessels within the central nervous system. Although stem cell therapy is a promising approach for treating ischemic stroke, the inflammatory, oxidative, and hypoxic environment generated by cerebral ischemia greatly reduces the survival and therapeutic effects of transplanted stem cells. Endothelial colony-forming cells (ECFCs) are a class of precursor cells with strong proliferative potential that can migrate and differentiate directly into mature vascular endothelial cells. Consequently, ECFCs can exert significant therapeutic and reparative effects in diseases associated with vascular injury. Monocyte chemoattractant protein-induced protein 1 (MCPIP-1) exerts multiple biological effects; however, no studies have yet reported its role in the angiogenic function of ECFCs. In this study, we performed Proteome Profiler™ Human Angiogenesis Antibody arrays and tandem mass tag protein profiling to investigate the effect of MCPIP-1 on ECFCs. We demonstrated that MCPIP-1 knockdown enhanced the proliferation, migration, and in vivo and in vitro angiogenic capacity of ECFCs by upregulating the transferrin receptor-activated AKT/m-TOR signaling pathway to promote cellular trophic factor secretion. Furthermore, we found that the lateral ventricular transplantation of ECFCs with lentiviral MCPIP-1 knockdown into mice with middle cerebral artery occlusion increased serum vacular endothelial growth factor(VEGF), angiopoietin-1, and HIF-1a levels, enhanced neovascularization and neurogenesis in the ischemic penumbra, reduced the size of cerebral infarcts, and promoted neurological recovery. Together, these findings suggest new avenues for enhancing the therapeutic efficacy of ECFCs.

3D Bio-printing For Skin Tissue Regeneration: Hopes and Hurdles

Abstract:

For many years, discovering the appropriate methods for the treatment of skin irritation has been challenging for specialists and researchers. Bio-printing can be extensively applied to address the demand for proper skin substitutes to improve skin damage. Nowadays, to make more effective bio-mimicking of natural skin, many research teams have developed cell-seeded bio-inks for bioprinting of skin substitutes. These loaded cells can be single or co-cultured in these structures. The present review gives a comprehensive overview of the methods, substantial parameters of skin bioprinting, examples of in vitro and in vivo studies, and current advances and challenges for skin tissue engineering.

Recent strategies for enhancing the therapeutic efficacy of stem cells in wound healing

Skin wound healing is a multi-stage process that depends on the coordination of multiple cells and mediators. Chronic or non-healing wounds resulting from the dysregulation of this process represent a challenge for the healthcare system. For skin wound management, there are various approaches to tissue recovery. For decades, stem cell therapy has made outstanding achievements in wound regeneration. Three major types of stem cells, including embryonic stem cells, adult stem cells, and induced pluripotent stem cells, have been explored intensely. Mostly, mesenchymal stem cells are thought to be an extensive cell type for tissue repair. However, the limited cell efficacy and the underutilized therapeutic potential remain to be addressed. Exploring novel and advanced treatments to enhance stem cell efficacy is an urgent need. Diverse strategies are applied to maintain cell survival and increase cell functionality. In this study, we outline current approaches aiming to improve the beneficial outcomes of cell therapy to better grasp clinical cell transformation.

Cellular human tissue-engineered skin substitutes investigated for deep and difficult to heal injuries

Wound healing is an important function of skin; however, after significant skin injury (burns) or in certain dermatological pathologies (chronic wounds), this important process can be deregulated or lost, resulting in severe complications. To avoid these, studies have focused on developing tissue-engineered skin substitutes (TESSs), which attempt to replace and regenerate the damaged skin. Autologous cultured epithelial substitutes (CESs) constituted of keratinocytes, allogeneic cultured dermal substitutes (CDSs) composed of biomaterials and fibroblasts and autologous composite skin substitutes (CSSs) comprised of biomaterials, keratinocytes and fibroblasts, have been the most studied clinical TESSs, reporting positive results for different pathological conditions. However, researchers' purpose is to develop TESSs that resemble in a better way the human skin and its wound healing process. For this reason, they have also evaluated at preclinical level the incorporation of other human cell types such as melanocytes, Merkel and Langerhans cells, skin stem cells (SSCs), induced pluripotent stem cells (iPSCs) or mesenchymal stem cells (MSCs). Among these, MSCs have been also reported in clinical studies with hopeful results. Future perspectives in the field of human-TESSs are focused on improving in vivo animal models, incorporating immune cells, designing specific niches inside the biomaterials to increase stem cell potential and developing three-dimensional bioprinting strategies, with the final purpose of increasing patient's health care. In this review we summarize the use of different human cell populations for preclinical and clinical TESSs under research, remarking their strengths and limitations and discuss the future perspectives, which could be useful for wound healing purposes.

Current Advanced Therapies Based on Human Mesenchymal Stem Cells for Skin Diseases

Skin disease may be related with immunological disorders, external aggressions, or genetic conditions. Injuries or cutaneous diseases such as wounds, burns, psoriasis, and scleroderma among others are common pathologies in dermatology, and in some cases, conventional treatments are ineffective. In recent years, advanced therapies using human mesenchymal stem cells (hMSCs) from different sources has emerged as a promising strategy for the treatment of many pathologies. Due to their properties; regenerative, immunomodulatory and differentiation capacities, they could be applied for the treatment of cutaneous diseases. In this review, a total of thirteen types of hMSCs used as advanced therapy have been analyzed, considering the last 5 years (2015-2020). The most investigated types were those isolated from umbilical cord blood (hUCB-MSCs), adipose tissue (hAT-MSCs) and bone marrow (hBM-MSCs). The most studied diseases were wounds and ulcers, burns and psoriasis. At preclinical level, in vivo studies with mice and rats were the main animal models used, and a wide range of types of hMSCs were used. Clinical studies analyzed revealed that cell therapy by intravenous administration was the advanced therapy preferred except in the case of wounds and burns where tissue engineering was also reported. Although in most of the clinical trials reviewed results have not been posted yet, safety was high and only local slight adverse events (mild nausea or abdominal pain) were reported. In terms of effectiveness, it was difficult to compare the results due to the different doses administered and variables measured, but in general, percentage of wound's size reduction was higher than 80% in wounds, Psoriasis Area and Severity Index and Severity Scoring for Atopic Dermatitis were significantly reduced, for scleroderma, parameters such as Modified Rodnan skin score (MRSC) or European Scleroderma Study Group activity index reported an improvement of the disease and for hypertrophic scars, Vancouver Scar Scale (VSS) score was decreased after applying these therapies. On balance, hMSCs used for the treatment of cutaneous diseases is a promising strategy, however, the different experimental designs and endpoints stablished in each study, makes necessary more research to find the best way to treat each patient and disease.

Adipose tissue-derived stem cells: a comparative review on isolation, culture, and differentiation methods

Adipose tissue-derived stem cells (ADSCs) are an available source of mesenchymal stem cells with the appropriate capacity to in vitro survive, propagate, and differentiate into cells from three lineages of ectoderm, mesoderm, and endoderm. The biological features of ADSCs depend on the donor physiology and health status, isolation procedure, culture conditions, and differentiation protocols used. Adipose tissue samples are provided by surgery and lipoaspiration-based methods and subjected to various mechanical and chemical digestion techniques to finally generate a heterogeneous mixture named stromal vascular fraction (SVF). ADSCs are purified through varied cell populations that exist within SVF and cultured under standard conditions to give rise to a highly rich resource of stem cells directly applied in the clinic or differentiated into a wide range of cells. The development and optimization of conventional isolation, expansion, and differentiation methods seem noteworthy to preserve the desirable biological functions of ADSCs in pre-clinical and clinical investigations.

Epithelial differentiation of human adipose-derived stem cells (hASCs) undergoing three-dimensional (3D) cultivation with collagen sponge scaffold (CSS) via an indirect co-culture strategy

BACKGROUND

Three-dimensional (3D) cultivation with biomaterials was proposed to facilitate stem cell epithelial differentiation for wound healing. However, whether human adipose-derived stem cells (hASCs) on collagen sponge scaffold (CSS) better differentiate to keratinocytes remains unclear.

METHODS

3D cultivation with CSS on hASC epidermal differentiation co-cultured with HaCaT cells at air-liquid interface (ALI) was compared with two-dimensional (2D) form and cultivation without "co-culture" or "ALI." Cellular morphology, cell adhesion, and growth condition were evaluated, followed by the protein and gene expression of keratin 14 (K14, keratinocyte specific marker).

RESULTS

Typical cobblestone morphology of keratinocytes was remarkably observed in co-cultured hASCs at ALI, but those seeded on the CSS exhibited more keratinocyte-like cells under an invert microscope and scanning electron microscope. Desired cell adhesion and proliferation were confirmed in 3D differentiation groups by rhodamine-labeled phalloidin staining, consistent with H&E staining. Compared with those cultured in 2D culture system or without "ALI," immunofluorescence staining and gene expression analysis revealed hASCs co-cultured over CSS expressed K14 at higher levels at day 15.

CONCLUSIONS

CSS is positive to promote epithelial differentiation of hASCs, which will foster a deeper understanding of artificial dermis in skin wound healing and regeneration.

Hypoxia enhances the wound-healing potential of adipose-derived stem cells in a novel human primary keratinocyte-based scratch assay

Preclinical studies have suggested that paracrine factors from adipose-derived stem cells (ASCs) promote the healing of chronic wounds, and that the exposure of ASCs to hypoxia enhances their wound healing effect. To aid the translation of these findings into clinical use, robust wound models are necessary to explore each aspect of wound healing. The aspect of re-epithelization is often studied in a scratch assay based on transformed keratinocytes. However, there are concerns regarding the validity of this model, since these cell lines differ from normal keratinocytes, both in terms of proliferative capacity and differentiation, and sensitivity to environmental cues. In this study, the main challenge of using primary keratinocytes to examine the effects of ASCs was identified to be their different requirements for calcium in the culture media. We confirmed that a high calcium content led to morphological and cytoskeletal changes in primary keratinocytes, and demonstrated that a low calcium content compromised the growth of ASCs. We found that it is possible to perform the wound healing assay with primary keratinocytes, if the conditioned media from the ASCs is dialyzed to reduce the calcium concentration. Additionally, using this model of re-epithelization, conditioned media from normoxic ASCs was shown to markedly increase the rate of wound closure by primary keratinocytes, and this effect was significantly enhanced with media from the hypoxia-exposed ASCs. These findings, which are in line with the observations from previous in vivo studies, highlight the validity of this modified assay to investigate the wound healing properties of ASCs in vitro.

Potential Therapeutic Applications of Adipose-Derived Mesenchymal Stem Cells

Stem cells are subdivided into two main categories: embryonic and adult stem cells. In principle, pluripotent embryonic stem cells might differentiate in any cell types of the organism, whereas the potential of adult stem cells would be more restricted. Although adult stem cells from bone marrow have been initially the most extensively studied, those derived from human adipose tissue have been lately more widely investigated, because of several advantages. First, they can be easily obtained in large amounts from subcutaneous adipose tissue, with minimal pain and morbidity for the patients during harvesting. In addition, they feature low immunogenicity and can differentiate not only in cells of mesodermal lineage (adipocytes, osteoblasts, chondrocytes and muscle cells), but also in cells of other germ layers, such as neural or epithelial cells. As their multilineage differentiation capabilities are increasingly highlighted, their possible use in cell-based regenerative medicine is now broadly explored. In fact, starting from in vitro observations, many studies have already entered the preclinical and clinical phases. In this review, because of our main scientific interest, adipogenic, osteogenic, chondrogenic, and neurogenic differentiation abilities of adipose-derived mesenchymal stem cells, as well as their possible therapeutic applications, are chiefly focused. In addition, their ability to differentiate toward muscle, epithelial, pancreatic, and hepatic cells is briefly reported.

Mesenchymal stromal cells: properties and role in management of cutaneous diseases

This review describes the current understanding and the potential use of mesenchymal stromal cells (MSCs) in cell-based therapies for clinical management of difficult wounds and other dermatoses. MSCs have been shown to possess many advantageous properties that make them a promising therapeutic modality in dermatology still under investigation. In fact, MSCs' ability to promote wound healing through its paracrine function and pro-angiogenic properties have generated increasing interest for treating acute and chronic wounds. There is also great interest in utilizing MSCs' immunological characteristics for therapeutic use especially for patients with debilitating systemic autoimmune and inflammatory skin conditions who have failed other therapies. Its role in aesthetics has also been explored with clinical data showing improvement of acne scars and wrinkles from photoaging. Clinical trials are underway investigating the safety and efficacy of MSCs in the treatment of different skin conditions such as acute burns, diabetic and venous stasis ulcers, epidermolysis bullosa and systemic sclerosis, among others. We anticipate that as our understanding of the characteristics and function of MSCs grow, so will its role in cell-based treatments of dermatological conditions.

Development of Synthetic and Natural Materials for Tissue Engineering Applications Using Adipose Stem Cells

Adipose stem cells have prominent implications in tissue regeneration due to their abundance and relative ease of harvest from adipose tissue and their abilities to differentiate into mature cells of various tissue lineages and secrete various growth cytokines. Development of tissue engineering techniques in combination with various carrier scaffolds and adipose stem cells offers great potential in overcoming the existing limitations constraining classical approaches used in plastic and reconstructive surgery. However, as most tissue engineering techniques are new and highly experimental, there are still many practical challenges that must be overcome before laboratory research can lead to large-scale clinical applications. Tissue engineering is currently a growing field of medical research; in this review, we will discuss the progress in research on biomaterials and scaffolds for tissue engineering applications using adipose stem cells.

The Immunomodulatory Effects of Mesenchymal Stem Cells in Prevention or Treatment of Excessive Scars

Excessive scars, including keloids and hypertrophic scars, result from aberrations in the process of physiologic wound healing. An exaggerated inflammatory process is one of the main pathophysiological contributors. Scars may cause pain, and pruritis, limit joint mobility, and cause a range of cosmetic deformities that affect the patient's quality of life. Extensive research has been done on hypertrophic scar and keloid formation that has resulted in the plethora of treatment and prevention methods practiced today. Mesenchymal stem cells, among their multifunctional roles, are known regulators of inflammation and have been receiving attention as a major candidate for cell therapy to treat or prevent excessive scars. This paper extensively reviews the body of research examining the mechanism and potential of stem cell therapy in the treatment of excessive scars.