Human skin specific long noncoding RNA HOXC13-AS regulates epidermal differentiation by interfering with Golgi-ER retrograde transport

After a skin injury, keratinocytes switch from a state of homeostasis to one of regeneration leading to the reconstruction of the epidermal barrier. The regulatory mechanism of gene expression underpinning this key switch during human skin wound healing is enigmatic. Long noncoding RNAs (lncRNAs) constitute a new horizon in the understanding of the regulatory programs encoded in the mammalian genome. By comparing the transcriptome of an acute human wound and skin from the same donor as well as keratinocytes isolated from these paired tissue samples, we generated a list of lncRNAs showing changed expression in keratinocytes during wound repair. Our study focused on HOXC13-AS, a recently evolved human lncRNA specifically expressed in epidermal keratinocytes, and we found that its expression was temporally downregulated during wound healing. In line with its enrichment in suprabasal keratinocytes, HOXC13-AS was found to be increasingly expressed during keratinocyte differentiation, but its expression was reduced by EGFR signaling. After HOXC13-AS knockdown or overexpression in human primary keratinocytes undergoing differentiation induced by cell suspension or calcium treatment and in organotypic epidermis, we found that HOXC13-AS promoted keratinocyte differentiation. Moreover, RNA pull-down assays followed by mass spectrometry and RNA immunoprecipitation analysis revealed that mechanistically HOXC13-AS sequestered the coat complex subunit alpha (COPA) protein and interfered with Golgi-to-endoplasmic reticulum (ER) molecular transport, resulting in ER stress and enhanced keratinocyte differentiation. In summary, we identified HOXC13-AS as a crucial regulator of human epidermal differentiation.

Implant Attributes or Patient Characteristics? Factors Affecting Outcome after Breast Augmentation in Transgender Women

Implant-based breast augmentation is a valuable tool for treatment of gender dysphoria in transgender women. The aim was to assess whether implant attributes, plane selection, and patient characteristics had an impact on the surgical outcome, and to compare these parameters between transgender and cisgender breast augmentations.

Methods

A cohort of transgender women who underwent breast augmentation at our department during 2009-2018 were retrospectively studied. The cohort was also compared with a cohort of 12,884 mainly cisgender women registered in the Swedish breast implant registry (BRIMP) during 2014-2019.

Results

A total of 143 transgender individuals were included, with a median follow-up of 5.7 years. Complications occurred in 20 patients (14.0%), four patients (2.8%) underwent acute reoperation, and 20 patients (14.0%) had secondary corrections. No differences were seen in complication rates when comparing prepectoral with subpectoral placement (15.1% versus 12.9%; P = 0.81); size, less than 400 mL versus greater than or equal to 400 mL (14.7% versus 13.3%; P = 0.81), or the shape of the implants, round versus anatomic (10.7% versus 22.2%; P = 0.10). In comparison with the cohort from BRIMP, the transgender cohort had more round implants (72.0% versus 60.7%; P < 0.01), larger implants (44.1% had volumes of 400-599 mL, compared with 25.4%; P < 0.0001), and more prepectoral placement (51.0% versus 7.3%; P < 0.0001). The risk of reoperation less than 30 days was 1.2% in BRIMP and 2.8% in the transgender cohort (P = 0.08).

Conclusions

In transgender women, implants are often larger, round, and placed prepectoral' compared with cisgender women. Despite these differences, complication rates were equivalent. Implant attributes, surgical techniques, and patient characteristics were not independently associated with the rate of complications.

Integrative small and long RNA omics analysis of human healing and nonhealing wounds discovers cooperating microRNAs as therapeutic targets

MicroRNAs (miR), as important epigenetic control factors, reportedly regulate wound repair. However, our insufficient knowledge of clinically relevant miRs hinders their potential therapeutic use. For this, we performed paired small and long RNA-sequencing and integrative omics analysis in human tissue samples, including matched skin and acute wounds collected at each healing stage and chronic nonhealing venous ulcers (VUs). On the basis of the findings, we developed a compendium (https://www.xulandenlab.com/humanwounds-mirna-mrna), which will be an open, comprehensive resource to broadly aid wound healing research. With this first clinical, wound-centric resource of miRs and mRNAs, we identified 17 pathologically relevant miRs that exhibited abnormal VU expression and displayed their targets enriched explicitly in the VU gene signature. Intermeshing regulatory networks controlled by these miRs revealed their high cooperativity in contributing to chronic wound pathology characterized by persistent inflammation and proliferative phase initiation failure. Furthermore, we demonstrated that miR-34a, miR-424, and miR-516, upregulated in VU, cooperatively suppressed keratinocyte migration and growth while promoting inflammatory response. By combining miR expression patterns with their specific target gene expression context, we identified miRs highly relevant to VU pathology. Our study opens the possibility of developing innovative wound treatment that targets pathologically relevant cooperating miRs to attain higher therapeutic efficacy and specificity.

Single-Cell Analysis Reveals Major Histocompatibility Complex II‒Expressing Keratinocytes in Pressure Ulcers with Worse Healing Outcomes

Pressure ulcer (PU) is a chronic wound often seen in patients with spinal cord injury and other bed-bound individuals, particularly in the elderly population. Despite its association with high mortality, the pathophysiology of PU remains poorly understood. In this study, we compared single-cell transcriptomic profiles of human epidermal cells from PU wound edges with those from uninjured skin and acute wounds in healthy donors. We identified significant shifts in the cell composition and gene expression patterns in PU. In particular, we found that major histocompatibility complex class II‒expressing keratinocytes were enriched in patients with worse healing outcomes. Furthermore, we showed that the IFN-γ in PU-derived wound fluid could induce major histocompatibility complex II expression in keratinocytes and that these wound fluid‒treated keratinocytes inhibited autologous T-cell activation. In line with this observation, we found that T cells from PUs enriched with major histocompatibility complex II⁺ keratinocytes produced fewer inflammatory cytokines. Overall, our study provides a high-resolution molecular map of human PU compared with that of acute wounds and intact skin, providing insights into PU pathology and the future development of tailored wound therapy.

Increased salvage rates with early reexploration: A retrospective analysis of 547 free flap cases

BACKGROUND

Free flap complications are generally rare, but not negligible since they may exert paramount impact on both patients and care providers. The aim of the study was to identify risk factors for reexploration and assess predictors associated with increased salvage rates.

METHODS

A retrospective cohort study was conducted for free flaps performed between 2006 and 2015. Patient demographics, indications and flap types were analyzed together with complications and time to reexploration.

RESULTS

Among 547 consecutive free flaps, 11.5% required acute reexploration. Hematoma together with vascular compromise was the main cause (41.9%) for reexploration, followed by hematoma only (19.4%), venous (16.1%) and arterial (6.5%) thrombosis. Hematoma was associated with an increased risk for concomitant vascular complication (p < 0.02). The incidence of total and partial flap necrosis was 3.5% and 3.7% respectively. There was an overall 71.4% salvage rate. The median time from detection of a compromised flap to reexploration was 3.0 h. Significantly higher salvage rates were observed for cases reexplored within (82.4%) compared to after (57.1%) 3.0 h (OR 3.50 (95% CI 1.10 to 11.13, p = 0.034)).

CONCLUSIONS

The current study highlights the importance of early intervention, including evacuation of hematomas that may lead to vascular compromise. Adequate monitoring of venous outflow was found necessary to improve flap salvage rates, whereas arterial complications were mainly related to persistent arterial injury in traumatized extremities with reduced salvage rates. Free flap surgery requires trained staff and immediate access to operating facilities to ensure high flap survival rates.

miR-19a/b and miR-20a Promote Wound Healing by Regulating the Inflammatory Response of Keratinocytes

Persistent and impaired inflammation impedes tissue healing and is a characteristic of chronic wounds. A better understanding of the mechanisms controlling wound inflammation is needed. In this study, we show that in human wound-edge keratinocytes, the expressions of microRNA (miR)-17, miR-18a, miR-19a, miR-19b, and miR-20a, which all belong to the miR-17∼92 cluster, are upregulated during wound repair. However, their levels are lower in chronic ulcers than in acute wounds at the proliferative phase. Conditional knockout of miR-17∼92 in keratinocytes as well as injection of miR-19a/b and miR-20a antisense inhibitors into wound edges enhanced inflammation and delayed wound closure in mice. In contrast, conditional overexpression of the miR-17∼92 cluster or miR-19b alone in mice keratinocytes accelerated wound closure in vivo. Mechanistically, miR-19a/b and miR-20a decreased TLR3-mediated NF-κB activation by targeting SHCBP1 and SEMA7A, respectively, reducing the production of inflammatory chemokines and cytokines by keratinocytes. Thus, miR-19a/b and miR-20a being crucial regulators of wound inflammation, the lack thereof may contribute to sustained inflammation and impaired healing in chronic wounds. In line with this, we show that a combinatory treatment with miR-19b and miR-20a improved wound healing in a mouse model of type 2 diabetes.

WAKMAR2, a Long Noncoding RNA Downregulated in Human Chronic Wounds, Modulates Keratinocyte Motility and Production of Inflammatory Chemokines

Chronic wounds represent a major and growing health and economic burden worldwide. A better understanding of molecular mechanisms of normal as well as impaired wound healing is needed to develop effective treatment. Herein we studied the potential role of long noncoding RNA LOC100130476 in skin wound repair. LOC100130476 is an RNA polymerase II-encoded polyadenylated transcript present in both cytoplasm and nucleus. We found that its expression was lower in wound-edge keratinocytes of human chronic wounds compared to normal wounds of healthy donors and intact skin. In cultured keratinocytes, LOC100130476 expression was induced by TGF-β signaling. By reducing LOC100130476 expression with antisense oligos or activating its transcription with CRISPR/Cas9 Synergistic Activation Mediator system, we showed that LOC100130476 restricted the production of inflammatory chemokines by keratinocytes, while enhancing cell migration. In line with this, knockdown of LOC100130476 impaired re-epithelization of human ex vivo wounds. Based on these results, we named LOC100130476 wound and keratinocyte migration-associated long noncoding RNA 2 (WAKMAR2). Moreover, we identified a molecular network that may mediate the biological function of WAKMAR2 in keratinocytes using microarray. In summary, our data suggest that WAKMAR2 is an important regulator of skin wound healing and its deficiency may contribute to the pathogenesis of chronic wounds.

Effects of a formalized collaboration between plastic and orthopedic surgeons in severe extremity trauma patients; a retrospective study

BACKGROUND

Severe trauma to the extremities often includes a combination of fractures and soft tissue injuries. Several publications support that the patient outcome is better when skeletal stabilization is followed by early soft-tissue coverage. In an effort to optimize the treatment of these patients, we established a formalized collaboration in 2008 between the Departments of reconstructive plastic surgery and orthopedics at the Karolinska University Hospital.

METHODS

A retrospective review was conducted for all patients who had suffered severe extremity trauma and received either a free or a pedicled flap for extremity reconstruction. We compared the management of patients 0-4 years before and 0-4 years after the collaboration started especially with respect to; choice of flap, time to flap coverage, number of operations/revisions, total in-hospital stay.

RESULTS

After initiation of the collaboration, the number of flaps increased from 13 flaps (5 free and 8 pedicled) to 44 flaps (21 free and 23 pedicled). Fewer postoperative revisions was seen, as well as shorter in-hospital stay.

CONCLUSIONS

The present study highlights the importance of formalized collaboration between orthopedic and plastic surgeons in severe extremity trauma patients. The concept of an interdisciplinary approach has led to an increased number of trauma patients referred for plastic surgical consultation, an increased number of flaps, fewer postoperative revisions and shorter hospital stay.

Lower extremity soft tissue reconstruction and amputation rates in patients with open tibial fractures in Sweden during 1998-2010

Background

The rates of soft tissue reconstruction and amputation after open tibial fractures have not been studied on a national perspective. We aimed to determine the frequency of soft tissue coverage after open tibial fracture as well as primary and secondary amputation rates.

Methods

Data on all patients (> = 15 years) admitted to hospital with open tibial fractures were extracted from the Swedish National Patient Register (1998–2010). All surgical procedures, re-admissions, and mechanisms of injury were analysed accordingly. The risk of amputation was calculated using logistic regression (adjusted for age, sex, mechanism of injury, reconstructive surgery and fixation method). The mean follow-up time was 6 (SD 3.8) years.

Results

Of 3,777 patients, 342 patients underwent soft tissue reconstructive surgery. In total, there were 125 amputations. Among patients with no reconstructive surgery, 2% (n = 68 patients) underwent amputation. In an adjusted analysis, patients older than 70 years (OR = 2.7, 95%, CI = 1.1-6) and those who underwent reconstructive surgery (OR = 3.1, 95% CI = 1.6-5.8) showed higher risk for amputation. Fixations other than intramedullary nailing (plate, external fixation, closed reduction and combination) as the only method were associated with a significant higher risk for amputation (OR 5.1-14.4). Reconstruction within 72 hours (3 days) showed better results than reconstruction between 4–90 days (p = 0.04).

Conclusions

The rate of amputations after open tibial fractures is low (3.6%). There is a higher risk for amputations with age above 70 (in contrast: male sex and tissue reconstruction are rather indicators for more severe soft tissue injuries). Only a small proportion of open tibial fractures need soft tissue reconstructive surgery. Reconstruction with free or pedicled flap should be performed within 72 hours whenever possible.

Adipogenic, chondrogenic and osteogenic differentiation of clonally derived human dermal fibroblasts

The apparent need of an autologous cell source for tissue engineering applications has led researchers to explore the presence of cells with stem cell plasticity in several human tissues. Dermal fibroblasts (FBs) are easy to harvest, expand in vitro and store, rendering them plausible candidates for cell-based therapies. The aim of the present study was to observe the effects of adipogenic, chondrogenic and osteogenic induction media on the phenotype of human FBs. Human preadipocytes obtained from fat tissue have been proposed as an adult stem cell source with suitable characteristics, and were used as control cells in regard to their differentiation potential. Routine staining, immunohistochemical analysis and alkaline phosphatase assay were employed, in order to study the phenotypic shift. FBs were shown to possess multilineage potential, giving rise to fat-, cartilage- and bone-like cells. To exclude contaminant progenitor cells or cell fusion giving rise to tissue with adipocyte-, chondrocyte- and osteoblast-like cells, single-cell cloning was performed. Single-cell-cloned FBs (sccFBs) displayed a similar differentiation potential as primary-culture FBs. The presence of 'stem-cell-specific' surface antigens was analyzed using flow cytometry. The results reveal that sccFBs have several of the markers associated with cells exhibiting stem cell plasticity. The findings presented here are corroborated by the findings of other groups, and suggest the use of human dermal FBs in cell-based therapies for the reconstruction of fat, cartilage and bone.