Aging is a multifactorial process that affects skin integrity through the progressive decline of dermal fibroblast function. Dermal fibroblasts are key regulators of extracellular matrix (ECM) composition, wound healing, and tissue homeostasis. However, their dysfunction contributes to structural deterioration, chronic inflammation, and impaired regenerative capacity. Cellular senescence, a fundamental characteristic of aging, results in the buildup of senescent fibroblasts that release growth factors, matrix-degrading enzymes, and pro-inflammatory cytokines, known as the senescence-associated secretory phenotype (SASP). This study examines the impact of fibroblast senescence on dermal aging, highlighting mechanisms such as DNA damage, mitochondrial dysfunction, oxidative stress, and telomere attrition. The role of SASP-driven ECM degradation, matrix metalloproteinases (MMPs) activation, and fibroblast-keratinocyte communication breakdown are explored, demonstrating their collective contribution to skin aging. Additionally, key signaling pathways, including p16INK4a/RB, p53, NF-κB, mTOR, and TGF-β, are implicated in fibroblast senescence and chronic inflammation. Recent advancements in therapeutic strategies targeting fibroblast aging, such as senolytics, extracellular vesicle-based interventions, and metabolic reprogramming, offer promising avenues for skin rejuvenation. This review delves into the molecular and cellular dynamics of dermal fibroblast aging, emphasizing their relevance for developing novel anti-aging interventions.

Background: Fat grafting is one of the most common soft tissue filling methods in plastic surgery. Bone marrow mesenchymal stem cell (BM-MSC) transplantation is an effective method for improving graft retention. However, the role of BM-MSCs in fat transplantation is not completely clear. Methods: Human fat particles, together with BM-MSCs or PBS as a control, were subcutaneously transplanted into the backs of nude mice. Samples were taken on days 14, 30 and 90 post-grafting to calculate the fat graft retention rate, and tissue staining was evaluated. Furthermore, macrophages were treated with BM-MSC conditioned medium (BM-MSC-CM) to identify the beneficial component secreted by these stem cells. Results: In this study, we found that BM-MSCs improved retention by enhancing angiogenesis in fat grafting. Further analysis revealed that BM-MSCs could significantly inhibit the expression of the proinflammatory M1 macrophage markers interleukin (IL)-1β, tumor necrosis factor-α (TNF-α) and IL-6 in the early stages of fat grafting and promote the expression of the anti-inflammatory M2 macrophage markers Arg1, IL-10 and VEGF. Furthermore, our results showed that IL-10 secreted by BM-MSCs induced M2 macrophage polarization in vitro. Conclusions: BM-MSC transplantation can improve the fat retention rate and promote angiogenesis, which may be related to M2 macrophages. These results help elucidate the role of BM-MSCs in fat grafting.

Decellularized adipose matrix provides an inductive microenvironment for stem cells in tissue regeneration

Wound healing remains a challenge worldwide, and an ideal wound dressing that promotes healing is urgently needed. In this study, we developed a thermosensitive injectable hydrogel known as the thermosensitive decellularized adipose tissue/platelet-rich plasma interpenetrating polymer network (t-DPI) hydrogel based on decellularized adipose tissue (DAT) and temperature-controlled platelet-rich plasma (t-PRP). Abundant platelets, growth factors (GFs), and bioactive substances from the decellularized extracellular matrix (dECM) in the t-DPI hydrogel had positive effects on wound healing. The morphology, thermosensitivity, and GFs release properties of the t-DPI hydrogel were studied. In vitro, the t-DPI hydrogel showed ideal cytocompatibility and the abilities to promote the proliferation, migration and tube formation of human umbilical vein endothelial cells (HUVECs). Moreover, M2 macrophage polarization was enhanced after treated with t-DPI hydrogel. In vivo, the t-DPI hydrogel notably accelerated the full-thickness wound healing. The positive role of the t-DPI hydrogel on pro-angiogenesis, macrophage polarization and collagen deposition were validated in the nude mouse full-thickness skin defect model. In addition, the clinical application potential was confirmed using a pre-clinical porcine full-thickness wound model. Overall, this study demonstrated that the t-DPI hydrogel achieves fast and ideal wound healing in full-thickness wound defects and provides a potential clinical treatment strategy.

Reduced sensitivity of prostate cancer (PC) cells to radiation therapy poses a significant challenge in the clinic. Activation of epidermal growth factor receptor (EGFR), type 1 insulin-like growth factor receptor (IGF1R), and crosstalk between these two signaling pathways have been implicated in the development of radiation resistance in PC. This study assessed the effects of targeting both receptors on the regulation of radio-sensitivity in PC cells. Specific inhibitors of EGFR and IGF1R, Erlotinib and AG1024, as well as siRNA targeting EGFR and IGF1R, were used to radio-sensitize PC cells. Our results showed that co-inhibiting both receptors significantly dampened cellular growth and DNA damage repair, and increased radio-sensitivity in PC cells. These effects were carried out through synergistic inhibition of homologous recombination-directed DNA repair (HRR), but not via inhibition of non-homologous end joining (NHEJ). Furthermore, the compromised HRR capacity was caused by reduced phosphorylation of insulin receptor substrate 1 (IRS1) and its subsequent interaction with Rad51. The synergistic effect of the EGFR and IGF1R inhibitors was also confirmed in nude mouse xenograft assay. This is the first study testing co-inhibiting EGFR and IGF1R signaling in the context of radio-sensitivity in PC and it may provide a promising adjuvant therapeutic approach to improve the outcome of PC patients to radiation treatment.