Cardiac fibroblasts are a major source of cardiac fibrosis during heart repair processes in various heart diseases. Although it has been shown that cardiac fibroblasts become senescent in response to heart injury, it is unknown how the senescence of cardiac fibroblasts is regulated in vivo. Gata4, a cardiogenic transcription factor essential for heart development, is also expressed in cardiac fibroblasts. However, it remains elusive about the role of Gata4 in cardiac fibroblasts. To define the role of Gata4 in cardiac fibroblasts, we generated cardiac fibroblast-specific Gata4 knockout mice by cross-breeding Tcf21-MerCreMer mice with Gata4^fl/fl mice. Using this mouse model, we could genetically ablate Gata4 in Tcf21 positive cardiac fibroblasts in an inducible manner upon tamoxifen administration. We found that cardiac fibroblast-specific deletion of Gata4 spontaneously induces senescence in cardiac fibroblasts in vivo and in vitro. We also found that Gata4 expression in both cardiomyocytes and non-myocytes significantly decreases in the aged heart. Interestingly, when αMHC-MerCreMer mice were bred with Gata4^fl/fl mice to generate cardiomyocyte-specific Gata4 knockout mice, no senescent cells were detected in the hearts. Taken together, our results demonstrate that Gata4 deficiency in cardiac fibroblasts activates a program of cellular senescence, suggesting a novel molecular mechanism of cardiac fibroblast senescence.

Background/Objective: A clinical need exists for more effective therapeutics and sustained drug delivery systems to promote ocular surface healing. This study tested the hypothesis that a novel biodegradable, thermoresponsive hydrogel loaded with the human recombinant (rh)MG53 protein, which we have demonstrated to promote corneal healing without fibrosis, would exhibit safety and biocompatibility in vitro and in vivo. Methods: Hydrogel optimization was performed based on varying concentrations of poloxamer 407, poloxamer 188, and hydroxypropyl methylcellulose. Hydrogels were characterized and potential toxicity was evaluated in vitro in cultured corneal epithelium, fibroblasts, and endothelium. In vivo safety and tolerability were assessed in mice and hydrogels were used to evaluate corneal healing following alkali injury. Results: The optimized hydrogel formulation did not result in any detrimental changes to the corneal cells and released functional rhMG53 protein for at least 24 h. In vivo rhMG53-loaded hydrogels improved re-epithelialization, reduced stromal opacification and vascularization, and promoted corneal nerve density. Mechanistically, rhMG53 reduced vascular endothelial cell migration and tube formation by inhibiting pSTAT3 signaling. Conclusions: Taken together, our poloxamer-based thermoresponsive hydrogel effectively released rhMG53 protein and enhanced multiple corneal healing outcomes.

Cardiac fibrosis is increasingly recognized as a dynamic program that resolves into a terminal fibroblast fate, the matrifibrocyte, rather than a persistent myofibroblast state. Lineage‐tracing and single‐cell studies reveal that matrifibrocytes arise from activated myofibroblasts during late scar maturation, lose α ‐SMA and proliferative capacity, and adopt a cartilage‐like ECM program (e.g., Comp , Chad , Thbs4 , Sfrp2 ). Functionally, they stabilize collagen architecture, sustain tensile strength and shape an immune‐quiescent, angiogenesis‐restrained microenvironment. We synthesize evidence suggesting that TGF‐ β restraint (e.g., Smad7 ), matrix mechanics (YAP/TAZ), Wnt attenuation ( Sfrp2 ), Comp–Notch3 feedback, and Thbs4–Atf6α ER‐stress adaptation converge to establish or maintain this terminal state. We further summarize disease contexts beyond infarction, including pressure overload and valvular disease, where matrifibrocyte‐like programs emerge and may contribute to chronic stiffening. Finally, we outline translational strategies that either accelerate matrifibrocyte maturation to secure scars after acute injury or reset terminal states via pharmacology or direct reprogramming to regress fibrosis. Framing matrifibrocytes as an adjustable endpoint reconciles structural integrity with functional recovery and highlights actionable checkpoints for precision anti‐fibrotic therapy.

Skeletal muscle regeneration declines with age despite the persistence of satellite cells, indicating that regenerative impairment reflects functional dysregulation rather than stem cell loss. Increasing evidence identifies early satellite cell activation as a stress-sensitive, rate-limiting checkpoint that is preferentially disrupted in aged muscle. Integrative analyses indicate that aged satellite cells exhibit elevated stress programs and reduced membrane remodeling capacity, accompanied by weakened activa-tion-associated transcriptional signatures, while proliferative and differentiation pro-grams remain relatively accessible in successfully activated cells. This imbalance is consistent with impaired activation fidelity, in which early instability drives compen-satory downstream responses at the expense of long-term self-renewal. Within this framework, MG53 (TRIM72) is positioned beyond its canonical role in myofiber mem-brane repair as a permissive, stress-responsive regulator that stabilizes the early acti-vation environment. Rather than directly specifying cell fate, MG53 is proposed to support early activation by limiting stress-associated membrane disruption and main-taining coordination of the activation program under age-related constraints. These ob-servations suggest that restoring activation quality, rather than amplifying proliferation, may represent a more durable strategy to preserve regenerative capacity in aging skeletal muscle.

Skeletal muscle regeneration declines with age despite the persistence of satellite cells (muscle stem cells, MuSCs), suggesting that regenerative impairment reflects functional dysregulation rather than MuSC depletion. Increasing evidence identifies early MuSC activation during the immediate post-injury period as a stress-sensitive, rate-limiting transition that is particularly vulnerable in aged muscle. Aged MuSCs exhibit elevated stress responses and reduced membrane remodeling capacity, accompanied by weakened activation-associated transcriptional induction. In contrast, proliferative and differentiation programs remain largely intact once activation is successfully initiated. These findings underscore that impaired coordination during early activation contributes to long-term regenerative decline in aging. Within this framework, MG53 (tripartite motif–containing protein 72, TRIM72), a muscle-enriched TRIM family E3 ubiquitin ligase originally identified as a mediator of sarcolemmal membrane repair, may also function as a stress-responsive regulator that stabilizes the early activation environment. Rather than directly determining cell fate, MG53 is proposed to facilitate activation by mitigating stress-associated membrane disruption and maintaining programmatic coordination under age-related physiological constraints. Most mechanistic evidence derives from rodent models, and direct validation in human aging muscle remains limited. These observations suggest that targeting early activation, rather than simply increasing proliferation, may better preserve regenerative capacity in aging skeletal muscle.

Fibroblast migration contributes to the spatial organization of tissue repair and extracellular matrix remodeling, but the transcriptional mechanisms regulating this process under physiologically relevant mechanical conditions remain incompletely understood. We investigated whether GATA4 regulates fibroblast migration in a tissue-of-origin-dependent manner. Cardiac fibroblasts (CFs), lung fibroblasts (LFs), and tail-tip fibroblasts (TTFs) were isolated from neonatal male and female Gata4 ^fl/fl mice and cultured on 8-kPa polydimethylsiloxane substrates. CF behavior on 8-kPa substrates was first compared with that on conventional tissue-culture plastic. Gata4 was subsequently deleted by adenoviral Cre transduction, and multiple features of steady-state migration were quantified by live-cell imaging. CFs cultured on 8-kPa substrates exhibited a smaller cell area and greater migration speed, displacement, and directional persistence than cells cultured on plastic, establishing a physiologically relevant mechanical baseline. Baseline Gata4 expression was highest in CFs, intermediate in LFs, and lowest in TTFs, whereas adenoviral Cre reduced Gata4 expression by more than 90% in all three populations. Gata4 deletion produced distinct migratory responses according to fibroblast source. In CFs, Gata4 loss reduced instantaneous speed, line speed, segment length, and directional persistence while increasing cell area. LFs showed modest increases in instantaneous speed, path speed, normalized 1-h path distance, and segment length without a clear change in directional persistence, whereas TTF migration was comparatively insensitive to Gata4 loss. Integrated effect-size analysis confirmed that the coordinated alteration of migration rate and directionality was most pronounced in CFs. RNA-seq analysis of adult CFs further showed enrichment of general motility and actin-remodeling programs following Gata4 deletion, without coordinated enrichment of lamellipodium and focal-adhesion programs. Together, these findings indicate that GATA4 supports efficient and persistent fibroblast migration in a fibroblast-source-dependent manner under physiologically relevant mechanical conditions.