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Significance: Skin scarring poses a major biomedical burden for hundreds of millions of patients annually. However, this burden could be mitigated by therapies that promote wound regeneration, with...

Significance: Wound healing is the largest medical market without an existing small molecule/drug treatment. Both “under-healing” (chronic wounds) and “over-healing” (scarring) cause a substantial ...

As of 2017, more than 30 million Americans—nearly 10% of the population—have diabetes (1). More than 1.5 million new cases of diabetes were diagnosed in 2015 (1). The prevalence of both type 1 and type 2 diabetes is rapidly increasing, and by 2050, diabetes is expected to affect more than one in five adults in the United States (2–5). The economic burden of diabetes is enormous and growing; in 2017, it was estimated to be $327 billion, including $237 billion in direct medical costs (6), a nearly twofold increase from 2007 (3). The 1.25 million American adults living with type 1 diabetes comprise 5.6% of all U.S. adults with a diabetes diagnosis (7). Because these patients are unable to produce sufficient endogenous insulin, they are reliant on exogenous insulin injections for their entire lives. In addition to individuals with type 1 diabetes, roughly 30% of patients with type 2 diabetes also require insulin therapy, typically in the setting of A1C levels that are uncontrolled with oral hypoglycemic agents (8–11). Recently, exorbitant insulin prices have dominated news headlines across the United States. In just 5 years, from 2012 to 2017, the cost of insulin increased by 110% (6). Insulin costs totaled more than $14 billion in 2017, not including required supplies and equipment, which were responsible for an additional $5 billion in costs (6). Beyond the sizeable economic burden of insulin use, long-term insulin administration can also cause a host of problems for patients. In particular, repeated insulin injections and insulin pump use often result in complications and changes in the skin at injection or pump sites (Figure 1) (12). The two most common injection site complications are: 1. Fibrosis, the accumulation of stiff, dense scar tissue at the injection site (Figure 1 A , middle …

Pathologic skin scarring presents a vast economic and medical burden. Unfortunately, the molecular mechanisms underlying scar formation remain to be elucidated. We used a hypertrophic scarring (HTS) mouse model in which Jun is overexpressed globally or specifically in α-smooth muscle or collagen type I–expressing cells to cause excessive extracellular matrix deposition by skin fibroblasts in the skin after wounding. Jun overexpression triggered dermal fibrosis by modulating distinct fibroblast subpopulations within the wound, enhancing reticular fibroblast numbers, and decreasing lipofibroblasts. Analysis of human scars further revealed that JUN is highly expressed across the wide spectrum of scars, including HTS and keloids. CRISPR-Cas9–mediated JUN deletion in human HTS fibroblasts combined with epigenomic and transcriptomic analysis of both human and mouse HTS fibroblasts revealed that JUN initiates fibrosis by regulating CD36. Blocking CD36 with salvianolic acid B or CD36 knockout model counteracted JUN-mediated fibrosis efficacy in both human fibroblasts and mouse wounds. In summary, JUN is a critical regulator of pathological skin scarring, and targeting its downstream effector CD36 may represent a therapeutic strategy against scarring.

Purpose: Crohn’s disease (CD) is a subtype of inflammatory bowel disease (IBD) characterized by patchy, transmural inflammation throughout the digestive tract and creeping fat formation. Thirty percent of CD patients develop strictures, eighty percent of which will require surgery. Creeping fat is associated with stricture formation, but its role in intestinal fibrosis remains unclear. Here, we present a novel surgical model of intestinal fibrosis and show by lineage tracing that creeping fat adipocytes convert to fibroblasts that contribute to fibrosis. Methods: We developed a novel surgical model of IBD that avoids the chronic use of caustic agents by creating a longitudinal, anti-mesenteric colotomy in the mouse transverse colon that is closed transversally. We performed Masson’s trichrome staining to assess collagen deposition. Finally, we performed lineage tracing of mature adipocytes in Adiponectin-Cre; mTmG mice and characterized adipocyte-derived cells by immunostaining. Results: Our surgical model mimics key features of human strictures, including the formation of creeping fat around the injury site, increased bowel wall thickness, collagen deposition, and transmural adipocyte infiltration by post-operative day (POD) 7. Immunostaining for adipocyte and fibroblast markers confirmed the presence of transmural adipocytes adjacent to fibroblasts. Lineage tracing of mature adipocytes in Adiponectin-Cre; mTmG mice revealed adipocyte-derived cells that infiltrate the wound site that lose expression of adipocyte lineage markers, gain expression of fibroblast markers, produce collagen, and respond to TGF-β signaling. Conclusions: Our novel surgical colotomy model represents a viable approach to study intestinal fibrosis and creeping fat without the long-term use of caustic agents. Lineage tracing of mature creeping fat adipocytes demonstrates that adipocytes convert to fibroblasts that infiltrate the injury site and participate in fibrotic responses. Taken together, these findings suggest that creeping fat contributes to intestinal fibrosis in part through the local conversion of adipocytes to fibroblasts.

Regeneration without scarring Wounds in adult mammals typically heal by forming fibrotic scars. Mascharak et al. found that a specific population of skin fibroblasts ( Engrailed-1 lineage–negative fibroblasts) activate expression of Engrailed-1 and turn on profibrotic cellular programs in response to local tissue mechanics in wounds (see the Perspective by Konieczny and Naik). When mechanical signaling was inhibited in these cells (using either genetic deletion or small-molecule inhibition), skin wounds in mice no longer formed scars but instead healed by regeneration, restoring skin with normal hair follicles and glands, extracellular matrix, and mechanical strength. Science , this issue p. eaba2374 ; see also p. 346

In the skin, tissue injury results in fibrosis in the form of scars composed of dense extracellular matrix deposited by fibroblasts. The therapeutic goal of regenerative wound healing has remained elusive in part because principles of fibroblast programming and adaptive response to injury remain incompletely understood. Here, we present a multimodal -omics platform for the comprehensive study of cell populations in complex tissue, which has allowed us to characterize the cells involved in wound healing across both time and space. We employ a stented wound model that recapitulates human tissue repair kinetics and multiple Rainbow transgenic lines to precisely track fibroblast fate during the physiologic response to injury. Through integrated analysis of single cell chromatin landscapes and gene expression states, coupled with spatial transcriptomic profiling, we are able to impute fibroblast epigenomes with temporospatial resolution. This has allowed us to define the mechanisms controlling cell fate during migration, proliferation, and differentiation following tissue injury and thereby reexamine the canonical phases of wound healing. These findings have broad implications for the study of tissue repair in complex organ systems.

Background:. Multiple publications have highlighted the prevalence of methicillin resistant Staphylococcus aureus (MRSA) as a cause of hand infections. We hypothesized that these publications have shifted the empiric treatment of hand infections. The aim of this study was to identify the current standard of care, the most common causative bacteria, and factors leading to extended length of stay for hand infection patients at a suburban hospital to improve treatment and establish an optimized care protocol. Methods:. Retrospective cohort analysis was conducted to identify all patients admitted for hand infections over an 8-year period. A comprehensive chart review of each patient’s hospital course was completed. Results:. A total of 70 patients were included. Maximum white blood cell count ≥ 12 was associated with a significantly longer hospital length of stay (9.1 days versus 5.4 days) compared to WBC values < 12 (P < 0.05). Also, 11 out of 23 (47.8%) underwent two or more incision and drainages (I&D’s), compared with patients with maximum WBC < 12. Vancomycin use as an empiric antibiotic was widespread (68 patients, 97.1%), despite only 14 (20%) having MRSA positive cultures. Univariate analysis identified a significant increased likelihood for increased length of stay (P < 0.05) and rise in creatinine (P < 0.05) in patients with an initial vancomycin trough level > 20. Conclusions:. This analysis of hand infection treatment in a suburban hospital demonstrates the incidence of MRSA hand infections may not be universally high across institutions. Each hospital should review its own data to optimize hand infection treatment and its associated costs.

Purpose: Scarring in the mouse dorsal dermis is mediated by pro-fibrotic, Engrailed-1 lineage-positive fibroblasts (EPFs). We recently showed that mechanotransduction blockade (YAP inhibition, using the drug verteporfin), results in complete wound regeneration, with full recovery of normal dermal appendages (hair follicles, glands), extracellular matrix (ECM) architecture, and tensile strength. This regenerative outcome following verteporfin treatment is mediated by Engrailed-1 lineage-negative fibroblasts (ENFs). The complex milieu of cell types and molecular signals involved in wound repair makes it difficult to study using any single data modality. Thus, we sought to use a holistic approach, incorporating multiple high-throughput, high-dimensional analyses, to define the divergent molecular events distinguishing typical scarring healing from verteporfin-induced wound regeneration. Methods: C57BL/6J mice underwent dorsal splinted excisional wounding per standard protocol. Wounds were treated with local injection of either verteporfin or vehicle control (PBS) on POD 0. We harvested unwounded skin and wounds at POD 2, 7, 14, and 30 (n=5 mice/timepoint and treatment) and subjected wound cells to three analyses: single-cell RNA-sequencing (scRNA-seq, using 10X Genomics Chromium); timsTOF, a recently-developed, high-throughput proteomic sequencing platform; and a novel machine learning algorithm for quantitatively comparing ECM ultrastructure. Results: Pseudotime analysis (Monocle3) of pooled scRNA-seq data revealed that fibroblasts followed two distinct transcriptional trajectories, one characterized by mechanical activation (En-1 lineage-positive, “fibrotic” trajectory) and the other characterized by developmental and regenerative pathways (En-1 lineage-negative; Rspo1, Dkk2/3, Trps1). Cross-platform data integration confirmed that fibroblasts in the fibrotic trajectory correlated with myofibroblast proteomic signatures (Col1a1/2, Fn1, etc.) and fibrotic/scar ECM features. In contrast, fibroblasts in the regenerative trajectory negatively correlated with myofibroblast markers and were associated with a “basket-weave” ECM pattern quantitatively indistinguishable from that of unwounded skin. Our integrated dataset suggested an important role for Wnt pathway proteins in ENF-mediated skin regeneration, so we compared POD 14 scars and regenerated wounds by multiplexed in situ hybridization (RNAScope) for Rspo1 (Wnt agonist), Trps1 (master hair follicle regulator), Ank1 (YAP target gene), and Dpp4 (EPF marker). Quantification of RNA granules across thousands of cells using a custom image analysis pipeline revealed that ENF-mediated healing (low Dpp4) in YAP-inhibited (low Ank1) wounds yielded regeneration of functional hair follicles through Wnt-mediated pathway activation (high Rpos1, Trps1). These data suggest that YAP inhibition unlocks wound regeneration via Wnt-active, En-1 lineage-negative fibroblasts. Conclusion: By studying regenerating (verteporfin-treated) versus scarring wounds across multiple healing timepoints and high-dimensional data modalities, we were able to profile fibrotic versus regenerative healing at unprecedented depth. Our integrated analysis revealed that dermal fibroblasts in these two wound settings exhibit distinct molecular trajectories defined by divergent transcriptomic, proteomic, and ultrastructural properties. Further, we found that wound regeneration in the context of verteporfin treatment is associated with suppression of mechanical signaling and activation of key Wnt pathway members including Trps1 (a gene with known hair follicle developmental roles). These results could have important implications for both the fundamental study of wound healing and potential anti-scarring therapeutic avenues

SummaryRegeneration is the “holy grail” of tissue repair, but skin injury typically yields fibrotic, non-functional scars. Developing pro-regenerative therapies requires rigorous understanding of the molecular progression from injury to fibrosis or regeneration. Here, we report the divergent molecular events driving skin wound cells toward either scarring or regenerative fates. We profile scarring versus YAP inhibition-induced wound regeneration at the transcriptional (single-cell RNA-sequencing), protein (timsTOF proteomics), and tissue (extracellular matrix ultrastructural analysis) levels. Using cell surface barcoding, we integrate these data to reveal fibrotic and regenerative “molecular trajectories” of healing. We show that disrupting YAP mechanical signaling yields regenerative repair orchestrated by fibroblasts with activated Trps1 and Wnt signaling. Our findings serve as a multimodal map of wound regeneration and could have therapeutic implications for pathologic fibroses.

Tissue fibrosis is the deposition of excessive extracellular matrix and can occur as part of the body's natural wound healing process upon injury, or as a consequence of diseases such as systemic sclerosis. Skin fibrosis contributes to significant morbidity due to the prevalence of injuries resulting from trauma and burn. Fibroblasts, the principal cells of the dermis, synthesize extracellular matrix to maintain the skin during homeostasis and also play a pivotal role in all stages of wound healing. Although it was previously believed that fibroblasts are homogeneous and mostly quiescent cells, it has become increasingly recognized that numerous fibroblast subtypes with unique functions and morphologies exist. This Review provides an overview of fibroblast heterogeneity in the mammalian dermis. We explain how fibroblast identity relates to their developmental origin, anatomical site and precise location within the skin tissue architecture in both human and mouse dermis. We discuss current evidence for the varied functionality of fibroblasts within the dermis and the relationships between fibroblast subtypes, and explain the current understanding of how fibroblast subpopulations may be controlled through transcriptional regulatory networks and paracrine communications. We consider how fibroblast heterogeneity can influence wound healing and fibrosis, and how insight into fibroblast heterogeneity could lead to novel therapeutic developments and targets for skin fibrosis. Finally, we contemplate how future studies should be shaped to implement knowledge of fibroblast heterogeneity into clinical practice in order to lessen the burden of skin fibrosis., Summary: This Review discusses the multifaceted aspects of fibroblast heterogeneity and the different roles of fibroblast subpopulations to help overcome skin scarring and fibrosis.

Skin scarring, the end result of adult wound healing, is detrimental to tissue form and function.

Randomized controlled trials are considered the gold standard in evidence-based medicine. The authors conducted a systematic review to evaluate the quantity, quality, and trends of randomized controlled trials that assess surgical treatment of carpal tunnel syndrome.The authors identified randomized controlled trials comparing two or more surgical interventions for carpal tunnel syndrome in PubMed, Cochrane, Scopus, Google Scholar, and Clinicaltrials.gov. Two independent reviewers evaluated articles for inclusion, extracted data, and assessed randomized controlled trial quality using the Jadad score.Of 2253 identified studies, 58 met full inclusion criteria. They were published between 1985 and 2015, with a significant increase over time (p = 0.003). They were most frequently published in Journal of Hand Surgery (European Volume) [n = 15 (25.9 percent)]. Most randomized controlled trials were single-center studies [n = 54 (93.1 percent)] conducted in the United Kingdom [n = 13 (22.4 percent)] or the United States [n = 10 (17.2 percent)], with a mean study size of 80.1 ± 55.5 patients. Funding source was unknown in 62.1 percent (n = 36). Three-quarters [n = 44 (75.9 percent)] of randomized controlled trials did not define the primary outcome measure(s). Less than 30 percent (n = 17) of randomized controlled trials conducted a power analysis. Only four studies with patients reported lost to follow-up provided an explanation for each patient. Six randomized controlled trials (10.3 percent) conducted intention-to-treat analysis. The mean Jadad score was 2.14 ± 1.26, with no significant improvement over time (p = 0.245).Despite the significant increase in the number of randomized controlled trials published studying surgical treatment of carpal tunnel syndrome over time, a mean Jadad score of 2.14 with no change over time indicates a need for improvement in quality. Proper study design is key to avoiding introduction of bias and ensuring the validity of conclusions drawn.

SUMMARY Fibroblast heterogeneity has been shown within the unwounded mouse dorsal dermis, with fibroblast subpopulations being identified according to anatomical location and embryonic lineage. Using lineage tracing, we demonstrate that paired related homeobox 1 (Prrx1)-expressing fibroblasts are responsible for acute and chronic fibroses in the ventral dermis. Single-cell transcriptomics further corroborated the inherent fibrotic characteristics of Prrx1 fibroblasts during wound repair. In summary, we identify and characterize a fibroblast subpopulation in the mouse ventral dermis with intrinsic scar-forming potential., In Brief Fibroblasts in the mouse dermis are heterogeneous, but it is unclear which subpopulation contributes to ventral scarring. Using lineage tracing and single-cell transcriptomics, Leavitt et al. report that Prrx1-expressing fibroblasts are largely responsible for fibrosis in the ventral dermis during wound repair., Graphical Abstract

OBJECTIVE: To investigate the effects of local doxycycline administration on skin scarring. BACKGROUND: Skin scarring represents a major source of morbidity for surgical patients. Doxycycline, a tetracycline antibiotic with off-target effects on the extracellular matrix, has demonstrated antifibrotic effects in multiple organs. However, doxycycline’s potential effects on skin scarring have not been explored in vivo. METHODS: Female C57BL/6J mice underwent dorsal wounding following an established splinted excisional skin wounding model. Doxycycline was administered by local injection into the wound base following injury. Wounds were harvested upon complete wound closure (postoperative day 15) for histological examination and biomechanical testing of scar tissue. RESULTS: A one-time dose of 3.90mM doxycycline (2mg/mL) within 12 hours of injury was found to significantly reduce scar thickness by 24.8% (*P < 0.0001) without compromising tensile strength. The same effect could not be achieved by oral dosing. In doxycycline-treated scar matrices, collagen I content was significantly reduced (*P = 0.0317) and fibers were favorably arranged with significantly increased fiber randomness (*P = 0.0115). Common culprits of altered wound healing mechanics, including angiogenesis and inflammation, were not impacted by doxycycline treatment. However, engrailed1 profibrotic fibroblasts, responsible for scar extracellular matrix deposition, were significantly reduced with doxycycline treatment (*P = 0.0005). CONCLUSIONS: Due to the substantial improvement in skin scarring and well-established clinical safety profile, locally administered doxycycline represents a promising vulnerary agent. As such, we favor rapid translation to human patients as an antiscarring therapy.

We assessed the quantity, quality and trends of randomized controlled trials comparing hand surgical interventions. Study characteristics were collected for 125 randomized controlled trials comparing hand surgical interventions. The Jadad scale (0–5), which assesses methodological quality of trials, was calculated. Logistic regressions were conducted to determine associations with the Jadad score. The studies were published between 1981 and 2015, with an increase over time, most often in Journal of Hand Surgery (European). Mean study size was 68 patients. Mean Jadad score was 2.1, without improvement over time. Thirty percent conducted a power analysis and 8% an intention-to-treat analysis. Studies conducted in the United Kingdom and with smaller sample sizes, power analysis and intention-to-treat analysis were associated with a higher Jadad score. The quantity of trials has increased over time while methodological quality has remained low, indicating a need to improve quality of trials in hand surgery literature.