AMPK activation eliminates senescent cells in diabetic wound by inducing NCOA4 mediated ferritinophagy.

BACKGROUND: Diabetic wounds are one of the long-term complications of diabetes, with a disordered microenvironment, diabetic wounds can easily develop into chronic non-healing wounds, which can impose a significant burden on healthcare. In diabetic condition, senescent cells accumulate in the wound area and suppress the wound healing process. AMPK, as a molecule related to metabolism, has a close relationship with aging and diabetes. The purpose of this study was to investigate the effects of AMPK activation on wound healing and explore the underlying mechanisms. METHODS: AMPK activator A769662 was topically applied in wound models of diabetic mice. Alterations in the wound site were observed and analyzed by immunohistochemistry. The markers related to autophagy and ferritinophagy were analyzed by western blotting and immunofluorescence staining. The role of AMPK activation and ferritinophagy were also analyzed by western blotting. RESULTS: Our results show that AMPK activation improved diabetic wound healing and reduced the accumulation of senescent cells. Intriguingly, we found that AMPK activation-induced ferroptosis is autophagy-dependent. We detected that the level of ferritin had deceased and NCOA4 was markedly increased after AMPK activation treatment. We further investigated that NCOA4-mediated ferritinophagy was involved in ferroptosis triggered by AMPK activation. Most importantly, AMPK activation can reverse the ferroptosis-insensitive of senescent fibroblast cells in diabetic mice wound area and promote wound healing. CONCLUSIONS: These results suggest that activating AMPK can promote diabetic wound healing by reversing the ferroptosis-insensitive of senescent fibroblast cells. AMPK may serve as a regulatory factor in senescent cells in the diabetic wound area, therefore AMPK activation can become a promising therapeutic method for diabetic non-healing wounds.

Multiomics Analysis Unravels Alteration in Molecule and Pathways Involved in Nondiabetic Chronic Wounds.

The prevalence of chronic wounds (CW) continues to grow. A thorough knowledge of the mechanism of CW formation remains elusive due to a lack of relevant studies. Furthermore, most previous studies concentrated on diabetic ulcers with relatively few investigations on other types. We performed this multiomics study to investigate the proteomic and metabolomic changes in wound and surrounding tissue from a cohort containing 13 patients with nondiabetic CW. Differentially expressed proteins (DEPs) and metabolites (DEMs) were filtered out and analyzed through multiomic profiling. The DEPs were further confirmed with the use of parallel reaction monitoring. Compared with the surrounding tissue, there were 82 proteins and 214 metabolites altered significantly in wound tissue. The DEPs were mainly enriched in focal adhesion (FA), extracellular matrix-receptor interaction (ERI), and the PI3K-Akt (PA) signaling pathway. Moreover, the DEMs were significantly enriched in amino sugar and nucleotide sugar metabolism and biosynthesis of nucleotide sugar pathways. In correlation analysis, we discovered that the PA signaling pathway, as well as its upstream and downstream pathways, coenriched some DEPs and DEMs. Additionally, we found that FBLN1, FBLN5, and EFEMP1 (FBLN3) proteins dramatically elevated in wound tissue and connected with the above signaling pathways. This multiomics study found that changes in FA, ERI, and PA signaling pathways had an impact on the cellular activities and functions of wound tissue cells. Additionally, increased expression of those proteins in wound tissue may inhibit vascular and skin cell proliferation and degrade the extracellular matrix, which may be one of the causes of CW formation.

Enzyme-responsive nanospheres target senescent cells for diabetic wound healing by employing chemodynamic therapy.

Evidence indicates that prolonged low-level inflammation and elevated-glucose-induced oxidative stress in diabetic wounds can accelerate senescence. The accumulation of senescent cells, in turn, inhibits cellular proliferation and migration, aggravating the inflammatory response and oxidative stress, ultimately impeding wound healing. In this study, we exploited the heightened lysosomal ß-galactosidase activity detected in senescent cells to develop an innovative drug delivery system by encapsulating Fe3O4 with galactose-modified poly (lactic-co-glycolic acid) (PLGA) (F@GP). We found that F@GP can selectively release Fe3O4 into senescent cells, inducing ferroptosis via the Fenton reaction in the presence of elevated intracellular H2O2 levels. This showed that F@GP administration can serve as a chemodynamic therapy to eliminate senescent cells and promote cell proliferation. Furthermore, the F@GP drug delivery system gradually released iron ions into the diabetic wound tissues, enhancing the attenuation of cellular senescence, stimulating cell proliferation, promoting re-epithelialization, and accelerating the healing of diabetic wounds in mice. Our groundbreaking approach unveiled the specific targeting of senescence by F@GP, demonstrating its profound effect on promoting the healing of diabetic wounds. This discovery underscores the therapeutic potential of F@GP in effectively addressing challenging cases of wound repair. STATEMENT OF SIGNIFICANCE: The development of galactose-modified PLGA nanoparticles loaded with Fe3O4 (F@GP) represents a significant therapeutic approach for the treatment of diabetic wounds. These nanoparticles exhibit remarkable potential in selectively targeting senescent cells, which accumulate in diabetic wound tissue, through an enzyme-responsive mechanism. By employing chemodynamic therapy, F@GP nanoparticles effectively eliminate senescent cells by releasing iron ions that mediate the Fenton reaction. This targeted approach holds great promise for promoting diabetic wound healing by selectively eliminating senescent cells, which play a crucial role in impairing the wound healing process. The innovative utilization of F@GP nanoparticles as a therapeutic intervention offers a novel and potentially transformative strategy for addressing the challenges associated with diabetic wound healing.

Erratum: Multifunctional sponge scaffold loaded with concentrated growth factors for promoting wound healing.

[This corrects the article DOI: 10.1016/j.isci.2022.105835.].

Strategies for improving the 3D printability of decellularized extracellular matrix bioink.

3D bioprinting is a revolutionary technology capable of replicating native tissue and organ microenvironments by precisely placing cells into 3D structures using bioinks. However, acquiring the ideal bioink to manufacture biomimetic constructs is challenging. A natural extracellular matrix (ECM) is an organ-specific material that provides physical, chemical, biological, and mechanical cues that are hard to mimic using a small number of components. Organ-derived decellularized ECM (dECM) bioink is revolutionary and has optimal biomimetic properties. However, dECM is always "non-printable" owing to its poor mechanical properties. Recent studies have focused on strategies to improve the 3D printability of dECM bioink. In this review, we highlight the decellularization methods and procedures used to produce these bioinks, effective methods to improve their printability, and recent advances in tissue regeneration using dECM-based bioinks. Finally, we discuss the challenges associated with manufacturing dECM bioinks and their potential large-scale applications.

Defective NCOA4-dependent ferroptosis in senescent fibroblasts retards diabetic wound healing.

Cellular senescence describes a state of permanent proliferative arrest in cells. Studies have demonstrated that diabetes promotes the pathological accumulation of senescent cells, which in turn impairs cell movement and proliferation. Historically, senescence has been perceived to be a detrimental consequence of chronic wound healing. However, the underlying mechanism that causes senescent cells to remain in diabetic wounds is yet to be elucidated. Ferroptosis and ferritinophagy observed in diabetes are due to iron metabolism disorders, which are directly associated with the initiation and progression of diabetes. Herein, we reveal that senescent fibroblasts in diabetic wounds are resistant to ferroptosis and that impaired ferritinophagy may be a contributing cause. Further, the expression of NCOA4, a key factor that influences ferritinophagy, is decreased in both diabetic wound tissue and high glucose-induced senescent fibroblasts. Moreover, NCOA4 overexpression could render senescent fibroblasts more vulnerable to ferroptosis. A faster wound healing process was also linked to the induction of ferroptosis. Thus, resistance to ferroptosis impedes the removal of senescent fibroblasts; promoting ferritinophagy could reverse this process, which may have significant implications for the management of diabetic wounds.

Recent Advances in Nano-Drug Delivery Systems for the Treatment of Diabetic Wound Healing.

Diabetes mellitus (DM) induced wound healing impairment remains a serious health problem and burden on the clinical obligation for high amputation rates. Based on the features of wound microenvironment, biomaterials loading specific drugs can benefit diabetic wound treatment. Drug delivery systems (DDSs) can carry diverse functional substances to the wound site. Nano-drug delivery systems (NDDSs), benefiting from their features related to nano size, overcome limitations of conventional DDSs application and are considered as a developing process in the wound treatment field. Recently, a number of finely designed nanocarriers efficiently loading various substances (bioactive and non-bioactive factors) have emerged to circumvent constraints faced by traditional DDSs. This review describes various recent advances of nano-drug delivery systems involved in mitigating diabetes mellitus-based non-healing wounds.

Multifunctional sponge scaffold loaded with concentrated growth factors for promoting wound healing.

Although both are applied in regenerative medicine, acellular dermal matrix (ADM) and concentrated growth factor (CGF) have their respective shortcoming: The functioning of CGF is often hindered by sudden release effects, among other problems, and ADM can only be used in outer dressing for wound healing. In this study, a compound network with physical-chemical double cross-linking was constructed using chemical cross-linking and the intertwining of ADM and chitosan chains under freezing conditions; equipped with good biocompatibility and cell/tissue affinity, the heparin-modified composite scaffold was able to significantly promote cell adhesion and proliferation to achieve adequate fixation and slow down the release of CGF; polydopamine nanoparticles having excellent near-infrared light photothermal conversion ability could significantly promote the survival of rat autologous skin grafts. In a word, this multifunctional composite scaffold is a promising new type of implant biomaterial capable of delivering CGF to promote the healing of full-thickness skin defects.

Polydopamine modified acellular dermal matrix sponge scaffold loaded with a-FGF: Promoting wound healing of autologous skin grafts.

Despite increasing potentials as a skin regeneration template (DRT) to guide tissue healing, acellular dermal matrix (ADM) is still challenged by issues (like dense architecture, low cellular adhesion and poor vascularization), contributing to necrosis and shedding of upper transplanted skins. Modified with polydopamine (PDA), a novel and porous DRT capable of drug delivery was designed using porcine-derived ADM (PADMS) gels, termed PDA-PADMS. However, it was unclear whether it could efficiently deliver human acidic fibroblast growth factor (a-FGF) and regenerate skin defects. Herein, after being fabricated and optimized with PADMS gels in different ratios (1:6, 1:7, 1:8), PDA-PADMS loading a-FGF (PDA-PADMS-FGF) was evaluated by the morphology, physical& chemical properties, drug release and in-vitro biological evaluations, followed by full-thickness skin defects implanted with PDA-PADMS-FGF covered by transplanted skins. Apart from containing abundant collagen and elastin, porous PADMS (with a loose and uniform structure) was demonstrated to possess controlled release of a-FGF and biocompatibility attributed to PDA coating. Consistent with augmented cellular migration and proliferation in vitro, PDA-PADMS-FGF also accelerated wound healing and reduced scarring, improving collagen arrangement and neovascularization. In conclusion, PDA-PADMS-FGF has a good potential and application prospect as a matrix material for wound repair.

Senescence in chronic wounds and potential targeted therapies.

Chronic wounds (e.g. diabetic wounds, pressure wounds, vascular ulcers, etc.) do not usually heal in a timely and orderly manner but rather last for years and may lead to irreversible adverse events, resulting in a substantial financial burden for patients and society. Recently, a large amount of evidence has proven that cellular senescence has a crucial influence on chronic nonhealing wounds. As a defensive mechanism, cell senescence is a manner of cell-cycle arrest with increased secretory phenotype to resist death, preventing cells from stress-induced damage in cancer and noncancer diseases. A growing amount of research has advanced the perception of cell senescence in various chronic wounds and focuses on pathological and physiological processes and therapies targeting senescent cells. However, previous reviews have failed to sum up novel understandings of senescence in chronic wounds and emerging strategies targeting senescence. Herein, we discuss the characteristics and mechanisms of cellular senescence and the link between senescence and chronic wounds as well as some novel antisenescence strategies targeting other diseases that may be applied for chronic wounds.

Association between genetically predicted leukocyte telomere length and non-scarring alopecia: A two-sample Mendelian randomization study.

Background: The most commonly acknowledged non-scarring alopecia are androgenetic alopecia (AGA) and alopecia areata (AA). Previous studies have revealed various risk factors associated with alopecia. However, the relationship between leukocyte telomere length (LTL) and non-scarring alopecia remains unclear. Methods: A two-sample Mendelian randomization (MR) analysis was performed to evaluate the causality between genetically predicted LTL and the risk of non-scarring alopecia. MR analyses were performed using the inverse variance-weighted (IVW) method and complemented with other MR methods. Results: The summary statistics of the genome-wide association studies (GWAS) for AGA and AA were obtained from the FinnGen biobank, which included 119,185 and 211,428 individuals, respectively. A total of 126 single nucleotide polymorphisms (SNPs) with genome-wide significance were selected as the instrumental variables for LTL. The MR analyses suggested a causal relationship between LTL and AGA, and the risk of AGA increased by 3.19 times as the genetically predicted LTL was shortened by one standard deviation in log transformed form under the IVW method (OR = 4.19, 95% CI = 1.20-14.61, p = 0.024). The other MR methods also demonstrated a similar trend of the effect of LTL on AGA. There was no causal relationship between LTL and AA (p > 0.05). Sensitivity analyses further demonstrated that the current results were less likely to be affected by confounders and bias. Conclusion: Our results suggested a potential causal relationship between LTL and AGA, and shortened LTL was associated with an increased risk of AGA.