Fibroblast Heterogeneity in Healthy and Wounded Skin

A comprehensive evaluation of dermal fibroblast therapy in clinical trials for treating skin disorders and cosmetic applications: a scoping review

BACKGROUND

Fibroblast cells have the ability to improve skin conditions through regenerative medicine and cell-based therapies. The purpose of this scoping review is to assess the contribution of fibroblast cells to skin homeostasis and extracellular matrix deposition in clinical trials involving skin disorders and cosmetic applications.

METHODS

Using targeted search terms, published publications from January 2000 to August 2023 that addressed fibroblast uses in clinical trials of skin conditions were obtained from bibliographic databases like PubMed, Scopus, and Web of Science (WoS). Precise inclusion and exclusion criteria were used during the screening process. The potential benefits of induction treatment with fibroblasts lead to the choosing of clinical trials for this kind of treatment.

RESULTS

Out of the 820 published ppapers initially identified, only 35 studies fulfilled our meticulous eligibility criteria after careful screening. To ensure clarity, we methodically eliminated any duplicate or irrelevant published papers, thereby offering a transparent account of our selection process.

CONCLUSION

This study highlights the advantages of fibroblast therapy in treating skin conditions such as diabetic foot, venous leg ulcers, and cosmetic reasons. Fibroblasts possess remarkable regenerating capabilities, making dermal fibroblast therapy crucial in cell-based and skin regenerative treatments. Nevertheless, additional research is required for more disorders and cosmetic applications.

Regulatory Mechanisms of Natural Active Ingredients and Compounds on Keratinocytes and Fibroblasts in Mitigating Skin Photoaging

Background

The mechanism underlying skin photoaging remains elusive because of the intricate cellular and molecular changes that contribute to this phenomenon, which have yet to be elucidated. In photoaging, the roles of keratinocytes and fibroblasts are vital for maintaining skin structure and elasticity. But these cells can get photo-induced damage during photoaging, causing skin morphological changes. Recently, the function of natural active ingredients in treating and preventing photoaging has drawn more attention, with researches often focusing on keratinocytes and fibroblasts.

Methods

We searched for studies published from 2007 to January 2024 in the Web of Science, PubMed, and ScienceDirect databases through the following keywords: natural plant, natural plant products or phytochemicals, traditional Chinese Medicine or Chinese herbal, plant extracts, solar skin aging, skin photoaging, and skin wrinkling. This review conducted the accordance of Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines.

Results

In total, 87 researches were included in this review (Figure 1). In keratinocytes, natural compounds may primarily regulate signal pathways such as the NF-κB, MAPK, PI3K/AKT, and Nrf2/ARE pathways, reducing inflammation and cellular damage, thus slowing skin photoaging. Additionally, in fibroblasts, natural active ingredients primarily promote the TGF-β pathway, inhibit MMPs activity, and enhance collagen synthesis while potentially modulating the mTOR pathway, thereby protecting the dermal collagen network and reducing wrinkle formation. Several trials showed that natural compounds that regulate keratinocytes and fibroblasts responses have significant and safe therapeutic effects.

Conclusion

The demand for natural product-based ingredients in sunscreen formulations is rising. Natural compounds show promising anti-photoaging effects by targeting cellular pathways in keratinocytes and fibroblasts, providing potential therapeutic strategies. However, comprehensive clinical studies are needed to verify their efficacy and safety in mitigating photoaging, which should use advanced pharmacological methods to uncover the complex anti-photoaging mechanisms of natural compounds.

The role of positional information in determining dermal fibroblast diversity

The largest mammalian organ, skin, consisting of a dermal connective tissue layer that underlies and supports the epidermis, acts as a protective barrier that excludes external pathogens and disseminates sensory signals emanating from the local microenvironment. Dermal connective tissue is comprised of a collagen-rich extracellular matrix (ECM) that is produced by connective tissue fibroblasts resident within the dermis. When wounded, a tissue repair program is induced whereby fibroblasts, in response to alterations in the microenvironment, produce new ECM components, resulting in the formation of a scar. Failure to terminate the normal tissue repair program causes fibrotic conditions including: hypertrophic scars, keloids, and the systemic autoimmune connective tissue disease scleroderma (systemic sclerosis, SSc). Histological and single-cell RNA sequencing (scRNAseq) studies have revealed that fibroblasts are heterogeneous and highly plastic. Understanding how this diversity contributes to dermal homeostasis, wounding, fibrosis, and cancer may ultimately result in novel anti-fibrotic therapies and personalized medicine. This review summarizes studies supporting this concept.

circ-Amotl1 in extracellular vesicles derived from ADSCs improves wound healing by upregulating SPARC translation

Aim

This study aims to explore the mechanism of circ- AMOT-like protein 1 (Amotl1) in extracellular vesicles (Evs) derived from adipose-derived stromal cells (ADSCs) regulating SPARC translation in wound healing process.

Methods

The morphology, wound healing rate of the wounds and Ki67 positive rate in mouse wound healing models were assessed by H&E staining and immunohistochemistry (IHC). The binding of IGF2BP2 and SPARC was verified by RNA pull-down. Adipose-derived stromal cells (ADSCs) were isolated and verified. The Evs from ADSCs (ADSC-Evs) were analyzed.

Results

Overexpression of SPARC can promote the wound healing process in mouse models. IGF2BP2 can elevate SPARC expression to promote the proliferation and migration of HSFs. circ-Amotl1 in ADSC-Evs can increase SPARC expression by binding IGF2BP2 to promote the proliferation and migration of HSFs.

Conclusion

ADSC-Evs derived circ-Amotl1 can bind IGF2BP2 to increase SPARC expression and further promote wound healing process.

Multiscale spatial mapping of cell populations across anatomical sites in healthy human skin and basal cell carcinoma

Our understanding of how human skin cells differ according to anatomical site and tumour formation is limited. To address this, we have created a multiscale spatial atlas of healthy skin and basal cell carcinoma (BCC), incorporating in vivo optical coherence tomography, single-cell RNA sequencing, spatial global transcriptional profiling, and in situ sequencing. Computational spatial deconvolution and projection revealed the localisation of distinct cell populations to specific tissue contexts. Although cell populations were conserved between healthy anatomical sites and in BCC, mesenchymal cell populations including fibroblasts and pericytes retained signatures of developmental origin. Spatial profiling and in silico lineage tracing support a hair follicle origin for BCC and demonstrate that cancer-associated fibroblasts are an expansion of a POSTN+ subpopulation associated with hair follicles in healthy skin. RGS5+ pericytes are also expanded in BCC suggesting a role in vascular remodelling. We propose that the identity of mesenchymal cell populations is regulated by signals emanating from adjacent structures and that these signals are repurposed to promote the expansion of skin cancer stroma. The resource we have created is publicly available in an interactive format for the research community.

Matricellular Proteins in the Homeostasis, Regeneration, and Aging of Skin

Matricellular proteins are secreted extracellular proteins that bear no primary structural functions but play crucial roles in tissue remodeling during development, homeostasis, and aging. Despite their low expression after birth, matricellular proteins within skin compartments support the structural function of many extracellular matrix proteins, such as collagens. In this review, we summarize the function of matricellular proteins in skin stem cell niches that influence stem cells' fate and self-renewal ability. In the epidermal stem cell niche, fibulin 7 promotes epidermal stem cells' heterogeneity and fitness into old age, and the transforming growth factor-β-induced protein ig-h3 (TGFBI)-enhances epidermal stem cell growth and wound healing. In the hair follicle stem cell niche, matricellular proteins such as periostin, tenascin C, SPARC, fibulin 1, CCN2, and R-Spondin 2 and 3 modulate stem cell activity during the hair cycle and may stabilize arrector pili muscle attachment to the hair follicle during piloerections (goosebumps). In skin wound healing, matricellular proteins are upregulated, and their functions have been examined in various gain-and-loss-of-function studies. However, much remains unknown concerning whether these proteins modulate skin stem cell behavior, plasticity, or cell-cell communications during wound healing and aging, leaving a new avenue for future studies.

Molecular Pathophysiology of Chronic Wounds: Current State and Future Directions

Venous leg ulcers, diabetic foot ulcers, and pressure ulcers are complex chronic wounds with multifactorial etiologies that are associated with high patient morbidity and mortality. Despite considerable progress in deciphering the pathologies of chronic wounds using "omics" approaches, considerable gaps in knowledge remain, and current therapies are often not efficacious. We provide a comprehensive overview of current understanding of the molecular mechanisms that impair healing and current knowledge on cell-specific dysregulation including keratinocytes, fibroblasts, immune cells, endothelial cells and their contributions to impaired reepithelialization, inflammation, angiogenesis, and tissue remodeling that characterize chronic wounds. We also provide a rationale for further elucidation of ulcer-specific pathologic processes that can be therapeutically targeted to shift chronic nonhealing to acute healing wounds.