Rapid isolation and expansion of skin-derived precursor cells from human primary fibroblast cultures

Impact of Combined Baricitinib and FTI Treatment on Adipogenesis in Hutchinson-Gilford Progeria Syndrome and Other Lipodystrophic Laminopathies

Hutchinson-Gilford progeria syndrome (HGPS) is a rare genetic disease that causes premature aging symptoms, such as vascular diseases, lipodystrophy, loss of bone mineral density, and alopecia. HGPS is mostly linked to a heterozygous and de novo mutation in the LMNA gene (c.1824 C > T; p.G608G), resulting in the production of a truncated prelamin A protein called "progerin". Progerin accumulation causes nuclear dysfunction, premature senescence, and apoptosis. Here, we examined the effects of baricitinib (Bar), an FDA-approved JAK/STAT inhibitor, and a combination of Bar and lonafarnib (FTI) treatment on adipogenesis using skin-derived precursors (SKPs). We analyzed the effect of these treatments on the differentiation potential of SKPs isolated from pre-established human primary fibroblast cultures. Compared to mock-treated HGPS SKPs, Bar and Bar + FTI treatments improved the differentiation of HGPS SKPs into adipocytes and lipid droplet formation. Similarly, Bar and Bar + FTI treatments improved the differentiation of SKPs derived from patients with two other lipodystrophic diseases: familial partial lipodystrophy type 2 (FPLD2) and mandibuloacral dysplasia type B (MADB). Overall, the results show that Bar treatment improves adipogenesis and lipid droplet formation in HGPS, FPLD2, and MADB, indicating that Bar + FTI treatment might further ameliorate HGPS pathologies compared to lonafarnib treatment alone.

Identification of a physiologic vasculogenic fibroblast state to achieve tissue repair

Tissue injury to skin diminishes miR-200b in dermal fibroblasts. Fibroblasts are widely reported to directly reprogram into endothelial-like cells and we hypothesized that miR-200b inhibition may cause such changes. We transfected human dermal fibroblasts with anti-miR-200b oligonucleotide, then using single cell RNA sequencing, identified emergence of a vasculogenic subset with a distinct fibroblast transcriptome and demonstrated blood vessel forming function in vivo. Anti-miR-200b delivery to murine injury sites likewise enhanced tissue perfusion, wound closure, and vasculogenic fibroblast contribution to perfused vessels in a FLI1 dependent manner. Vasculogenic fibroblast subset emergence was blunted in delayed healing wounds of diabetic animals but, topical tissue nanotransfection of a single anti-miR-200b oligonucleotide was sufficient to restore FLI1 expression, vasculogenic fibroblast emergence, tissue perfusion, and wound healing. Augmenting a physiologic tissue injury adaptive response mechanism that produces a vasculogenic fibroblast state change opens new avenues for therapeutic tissue vascularization of ischemic wounds.

Facilitation of mouse skin-derived precursor growth and yield by optimizing plating density

Multiple methodologies have been reported to facilitate skin-derived precursor (SKP) growth, but the impact of plating density on SKP growth has not been studied. To determine the optimal plating density, we used six plating densities and two types of flasks for mouse SKP (mSKP) culture. On the 14th day, the number, diameter, and viability of mSKP spheres were compared by morphological assessment and cell counting kit 8, and we found the optimal plating density was 2.5 × 10⁵–5 × 10⁵ cells/mL. In addition, we investigated the correlation between the SKP spheres and the adherent cell colonies in the serum-free culture system. We treated the adherent cell colonies with two culture conditions and characterized the cells generated from two conditions by immunocytochemistry and induced differentiation, respectively. The results elucidated that the adherent cell colonies differentiated into either mSKPs or dermal mesenchymal stem cells under appropriate culture conditions. In conclusion, mSKP spheres differentiated from the adherent cell colonies. The optimal plating density significantly promoted and advanced the proliferation of adherent cell colonies, which optimized mSKP growth and yield. The adherent cell colonies possessed the capacity of differentiating into different types of cells under appropriate culture conditions.

Impact of Progerin Expression on Adipogenesis in Hutchinson-Gilford Progeria Skin-Derived Precursor Cells

Hutchinson–Gilford progeria syndrome (HGPS) is a segmental premature aging disease caused by a mutation in LMNA. The mutation generates a truncated and farnesylated form of prelamin A, called progerin. Affected individuals develop several features of normal aging, including lipodystrophy caused by the loss of general subcutaneous fat. To determine whether premature cellular senescence is responsible for the altered adipogenesis in patients with HGPS, we evaluated the differentiation of HGPS skin-derived precursor stem cells (SKPs) into adipocytes. The SKPs were isolated from primary human HGPS and normal fibroblast cultures, with senescence of 5 and 30%. We observed that the presence of high numbers of senescent cells reduced SKPs’ adipogenic differentiation potential. Treatment with baricitinib, a JAK–STAT inhibitor, ameliorated the ability of HGPS SKPs to differentiate into adipocytes. Our findings suggest that the development of lipodystrophy in patients with HGPS may be associated with an increased rate of cellular senescence and chronic inflammation.

Ex Vivo Generation and Characterization of Human Hyaline and Elastic Cartilaginous Microtissues for Tissue Engineering Applications

Considering the high prevalence of cartilage-associated pathologies, low self-repair capacity and limitations of current repair techniques, tissue engineering (TE) strategies have emerged as a promising alternative in this field. Three-dimensional culture techniques have gained attention in recent years, showing their ability to provide the most biomimetic environment for the cells under culture conditions, enabling the cells to fabricate natural, 3D functional microtissues (MTs). In this sense, the aim of this study was to generate, characterize and compare scaffold-free human hyaline and elastic cartilage-derived MTs (HC-MTs and EC-MTs, respectively) under expansion (EM) and chondrogenic media (CM). MTs were generated by using agarose microchips and evaluated ex vivo for 28 days. The MTs generated were subjected to morphometric assessment and cell viability, metabolic activity and histological analyses. Results suggest that the use of CM improves the biomimicry of the MTs obtained in terms of morphology, viability and extracellular matrix (ECM) synthesis with respect to the use of EM. Moreover, the overall results indicate a faster and more sensitive response of the EC-derived cells to the use of CM as compared to HC chondrocytes. Finally, future preclinical in vivo studies are still needed to determine the potential clinical usefulness of these novel advanced therapy products.

Exosomes derived from autologous dermal fibroblasts promote diabetic cutaneous wound healing through the Akt/β-catenin pathway

Diabetic cutaneous wounds are one of the complications of diabetes mellitus (DM) and are difficult to cure at present. Autologous dermal fibroblasts (DFs) have shown great promise in skin regeneration and repair. However, whether exosomes derived from autologous dermal fibroblasts (DF-Ex) can be used to accelerate diabetic cutaneous wound healing is unclear. In this study, human umbilical vein endothelial cells (HUVECs) were treated with high glucose. We found that DF-Ex could reverse the damage produced by high glucose in HUVECs in vitro. A high-fat diet and streptozotocin were used to establish a rat model of type 2 diabetes mellitus (T2DM), and a diabetic cutaneous wound model was established in the T2DM rats. We discovered that subcutaneous injections of DF-Ex could significantly promote re-epithelialization, collagen deposition, skin cell proliferation, angiogenesis and inhibit inflammation to accelerate diabetic cutaneous wound healing. We further explored the underlying mechanism and found that DF-Ex exerted positive effects by activating the Akt/β-catenin pathway. This research revealed that DF-Ex may provide a new treatment strategy for diabetic cutaneous wound healing.

Functional hair follicle regeneration: an updated review

The hair follicle (HF) is a highly conserved sensory organ associated with the immune response against pathogens, thermoregulation, sebum production, angiogenesis, neurogenesis and wound healing. Although recent advances in lineage-tracing techniques and the ability to profile gene expression in small populations of cells have increased the understanding of how stem cells operate during hair growth and regeneration, the construction of functional follicles with cycling activity is still a great challenge for the hair research field and for translational and clinical applications. Given that hair formation and cycling rely on tightly coordinated epithelial-mesenchymal interactions, we thus review potential cell sources with HF-inducive capacities and summarize current bioengineering strategies for HF regeneration with functional restoration.

Glycocalyx disruption enhances motility, proliferation and collagen synthesis in diabetic fibroblasts

Impaired wound healing represents one of the most debilitating side effects of Diabetes mellitus. Though the role of fibroblasts in wound healing is well-known, the extent to which their function is altered in the context of diabetes remains incompletely understood. Here, we address this question by comparing the phenotypes of healthy dermal fibroblasts (HDFs) and diabetic dermal fibroblasts (DDFs). We show that DDFs are more elongated but less motile and less contractile than HDFs. Reduced motility of DDFs is attributed to formation of larger focal adhesions stabilized by a bulky glycocalyx, associated with increased expression of the cell surface glycoprotein mucin 16 (MUC 16). Disruption of the glycocalyx not only restored DDF motility to levels comparable to that of HDFs, but also led to increased proliferation and collagen synthesis. Collectively, our results illustrate the influence of glycocalyx disruption on mechanics of diabetic fibroblasts relevant to cell motility.

Lamin A involvement in ageing processes

Lamin A, a main constituent of the nuclear lamina, is the major splicing product of the LMNA gene, which also encodes lamin C, lamin A delta 10 and lamin C2. Involvement of lamin A in the ageing process became clear after the discovery that a group of progeroid syndromes, currently referred to as progeroid laminopathies, are caused by mutations in LMNA gene. Progeroid laminopathies include Hutchinson-Gilford Progeria, Mandibuloacral Dysplasia, Atypical Progeria and atypical-Werner syndrome, disabling and life-threatening diseases with accelerated ageing, bone resorption, lipodystrophy, skin abnormalities and cardiovascular disorders. Defects in lamin A post-translational maturation occur in progeroid syndromes and accumulated prelamin A affects ageing-related processes, such as mTOR signaling, epigenetic modifications, stress response, inflammation, microRNA activation and mechanosignaling. In this review, we briefly describe the role of these pathways in physiological ageing and go in deep into lamin A-dependent mechanisms that accelerate the ageing process. Finally, we propose that lamin A acts as a sensor of cell intrinsic and environmental stress through transient prelamin A accumulation, which triggers stress response mechanisms. Exacerbation of lamin A sensor activity due to stably elevated prelamin A levels contributes to the onset of a permanent stress response condition, which triggers accelerated ageing.

Multipotentiality of skin-derived precursors: application to the regeneration of skin and other tissues

Skin-derived precursors (SKPs) have been described as multipotent dermal precursors. Here, we provide a review of the breadth and depth of scientific literature and studies regarding SKPs, accounting for a large number of scientific publications. Interestingly, these progenitors can be isolated from embryonic and adult skin, as well as from a population of dermal cells cultured in vitro in monolayer. Gathering information from different authors, this review explores different aspects of the SKP theme, such as the potential distinct origins of SKPs in rodents and in humans, and also their ability to differentiate in vitro and in vivo into multiple lineages of different progeny. This remarkable capacity makes SKPs an interesting endogenous source of precursors to explore in the framework of experimental and therapeutic applications in different domains. SKPs are not only involved in the skin's dermal maintenance and support as well as wound healing, but also in hair follicle morphogenesis. This review points out the interests of future researches on SKPs for innovative perspectives that may be helpful in many different types of scientific and medical domains.

Insights into Fibroblast Plasticity: Cellular Communication Network 2 Is Required for Activation of Cancer-Associated Fibroblasts in a Murine Model of Melanoma

Tumor stroma resembles a fibrotic microenvironment, being characterized by the presence of myofibroblast-like cancer-associated fibroblasts (CAFs). In wild-type mice injected with melanoma cells, we show that the stem cell transcription factor Sox2 is expressed by tumor cells and induced in CAFs derived from synthetic fibroblasts. These fibroblasts were labeled postnatally with green fluorescent protein using mice expressing a tamoxifen-dependent Cre recombinase under the control of a fibroblast-specific promoter/enhancer. Conversely, fibroblast activation was impaired in mice with a fibroblast-specific deletion of cellular communication network 2 (Ccn2), associated with reduced expression of α-smooth muscle actin and Sox2. Multipotent Sox2-expressing skin-derived precursor (SKP) spheroids were cultured from murine back skin. Using lineage tracing and flow cytometry, approximately 40% of SKPs were found to be derived from type I collagen-lineage cells and acquired multipotency in culture. Inhibition of mechanotransduction pathways prevented myofibroblast differentiation of SKPs and expression of Ccn2. In SKPs deleted for Ccn2, differentiation into a myofibroblast, but not an adipocyte or neuronal phenotype, was also impaired. In human melanoma, CCN2 expression was associated with a profibrotic integrin alpha (ITGA) 11-expressing subset of CAFs that negatively associated with survival. These results suggest that synthetic dermal fibroblasts are plastic, and that CCN2 is required for the differentiation of dermal progenitor cells into a myofibroblast/CAF phenotype and is, therefore, a therapeutic target in melanoma.

Isolation, Characterization, and Safety Evaluation of Human Skin-Derived Precursors from an Adherent Monolayer Culture System

Background

Skin-derived precursors (SKPs) are promising candidates for regenerative medicine. Several studies have transcultured human SKPs (termed tSKPs) from fibroblasts (FBs) expanded in monolayer culture. Herein, we optimized the procedure by treating flasks with poly-2-hydroxyethyl methacrylate (poly-HEMA).

Methods

tSKPs generated from our adherent monolayer culture system were investigated for protein expression and differentiation capacity. The aggregated cells and the proliferative cells within tSKP spheres were detected by mix-culturing FBs expressing two different fluorescent proteins and BrdU- or EdU-positive cells, respectively. To distinguish tSKPs from FBs, we compared their phenotypes and transcriptomes. The tumorigenicity of tSKPs and FBs was also assessed in our study.

Results

tSKPs expressed Versican, Fibronectin, Vimentin, Sox2, and Nestin. Under appropriate stimuli, tSKPs could differentiate to mesenchymal or neural lineages. While these spheres were heterogeneous populations consisting of both proliferative and aggregated cells, the rate of proliferative cells correlated with a seeding density. tSKPs, isolated from FBs, were distinctive from FBs in cell cycle, marker expression, neural differentiation potential, and transcript profiles despite the two sharing partial similarity in certain properties. As for tumorigenesis, both tSKPs and FBs could be considered as nontumorigenic ex vivo and in vivo.

Conclusion

tSKPs were heterogeneous populations presenting similar characteristics as traditional SKPs, while being different from FBs. The potential mixture of FBs in spheres did not affect the biosafety of tSKPs, as both of which had normal karyotype and nontumorigenicity. Taken together, we suggested tSKPs had potential applications in regenerative medicine.

The Human Skin-Derived Precursors for Regenerative Medicine: Current State, Challenges, and Perspectives

Skin-derived precursors (SKPs) are an adult stem cell source with self-renewal and multipotent differentiation. Although rodent SKPs have been discussed in detail in substantial studies, human SKPs (hSKPs) are rarely reported. Understanding the biological properties and possible mechanisms underlying hSKPs has important implications for regenerative medicine particularly clinical applications, as human-derived sources are more suitable for clinical transplantation. The finding that hSKPs derivatives, such as neural and mesodermal progeny, have both in vitro and in vivo function without any genetical modification makes hSKPs a trustable, secure, and accessible resource for cell-based therapy. Here, we provide an overview of hSKPs, describing their characteristics, originations and niches, and potential applications. A comparison between traditional and innovative culture methods used for hSKPs is also introduced. Furthermore, we discuss the challenges and the future perspectives towards the field of hSKPs. With this review, we hope to point out the current stage of hSKPs and highlight the problems that remain in this field.