Establishing a Xenograft Model with CD-1 Nude Mice to Study Human Skin Wound Repair

BACKGROUND

A significant gap exists in the translatability of small-animal models to human subjects. One important factor is poor laboratory models involving human tissue. Thus, the authors have created a viable postnatal human skin xenograft model using athymic mice.

METHODS

Discarded human foreskins were collected following circumcision. All subcutaneous tissue was removed from these samples sterilely. Host CD-1 nude mice were then anesthetized, and dorsal skin was sterilized. A 1.2-cm-diameter, full-thickness section of dorsal skin was excised. The foreskin sample was then placed into the full-thickness defect in the host mice and sutured into place. Xenografts underwent dermal wounding using a 4-mm punch biopsy after engraftment. Xenografts were monitored for 14 days after wounding and then harvested.

RESULTS

At 14 days postoperatively, all mice survived the procedure. Grossly, the xenograft wounds showed formation of a human scar at postoperative day 14. Hematoxylin and eosin and Masson trichome staining confirmed scar formation in the wounded human skin. Using a novel artificial intelligence algorithm using picrosirius red staining, scar formation was confirmed in human wounded skin compared with the unwounded skin. Histologically, CD31 + immunostaining confirmed vascularization of the xenograft. The xenograft exclusively showed human collagen type I, CD26 + , and human nuclear antigen in the human scar without any staining of these human markers in the murine skin.

CONCLUSION

The proposed model demonstrates wound healing to be a local response from tissue resident human fibroblasts and allows for reproducible evaluation of human skin wound repair in a preclinical model.

CLINICAL RELEVANCE STATEMENT

Radiation-induced fibrosis is a widely prevalent clinical phenomenon without a well-defined treatment at this time. This study will help establish a small-animal model to better understand and develop novel therapeutics to treat irradiated human skin.

Allele-specific expression reveals genetic drivers of tissue regeneration in mice

In adult mammals, skin wounds typically heal by scarring rather than through regeneration. In contrast, "super-healer" Murphy Roths Large (MRL) mice have the unusual ability to regenerate ear punch wounds; however, the molecular basis for this regeneration remains elusive. Here, in hybrid crosses between MRL and non-regenerating mice, we used allele-specific gene expression to identify cis-regulatory variation associated with ear regeneration. Analyzing three major cell populations (immune, fibroblast, and endothelial), we found that genes with cis-regulatory differences specifically in fibroblasts were associated with wound-healing pathways and also co-localized with quantitative trait loci for ear wound-healing. Ectopic treatment with one of these proteins, complement factor H (CFH), accelerated wound repair and induced regeneration in typically fibrotic wounds. Through single-cell RNA sequencing (RNA-seq), we observed that CFH treatment dramatically reduced immune cell recruitment to wounds, suggesting a potential mechanism for CFH's effect. Overall, our results provide insights into the molecular drivers of regeneration with potential clinical implications.

Leadership Trends at Hand Surgery Fellowships

BACKGROUND

Fellowship directors (FDs) influence the future of trainees in the field of hand surgery. Currently, there are no studies that analyze the demographic background, institutional training, and academic experience of hand surgery FDs. This study aims to serve as a framework to understand the landscape of current leadership positions in hand surgery education and to identify opportunities to improve FD diversity.

METHODS

The American Society for Surgery of the Hand Fellowship Directory was reviewed to include all hand surgery fellowships in the United States. Collected demographic information regarding FDs included age, sex, ethnicity, residency/fellowship training, residency/fellowship graduation year, year hired by current institution, time since training completion until FD appointment, length in FD role, and H-index.

RESULTS

Of the 90 FDs included, 86.7% were men and 71.4% self-reported as Caucasian. The average H-index was 13.98 and significantly correlated with age and duration as FD; 71.1% of FDs were trained in orthopedic surgery. The most attended residency program was the University of Pennsylvania; Mayo Clinic and Harvard University were the most represented fellowship programs.

CONCLUSION

This review reveals specific trends in demographic backgrounds, institutional training, and academic experiences among current FDs in hand surgery. Our observations, such as racial/ethnic and sex disparities, may offer opportunities to improve the representation of the communities these physicians serve. In addition, the trends described in this study provide objective data among current hand surgery FDs and could serve as a guide for individuals who desire academic leadership roles.

Reduction of Tendon Fibrosis Using Galectin-3 Inhibitors

BACKGROUND

Fibrosis is a complication of both tendon injuries and repairs. We aim to develop a mouse model to assess tendon fibrosis and to identify an antifibrotic agent capable of overcoming tendon fibrosis.

METHODS

Adult C57Bl/6 mice underwent a skin incision to expose the Achilles tendon, followed by 50% tendon injury and abrasion with sandpaper. Sham surgeries were conducted on contralateral hindlimbs. Histology and immunofluorescent staining for fibrotic markers (Col1, α-SMA) were used to confirm that the model induced tendon fibrosis. A second experiment was conducted to further examine the role of α-SMA in adhesion formation using α-SMA.mTmG mice (6-8 weeks old) (n=3) with the same injury model. The control group (tendon injury) was compared to the sham group, using the contralateral limb with skin incision only. A second experiment was conducted to further examine the role of α-SMA in adhesion formation using α-SMA.mTmG mice (6-8 weeks old) (n=3) with the same injury model. The control group (tendon injury) was compared to the sham group, using the contralateral limb with skin incision only. Lastly, α-SMA.mTmG mice were randomized to either condition 1. Tendon injury (control group) or 2. Tendon injury with Galectin-3 inhibitor (Gal3i) treatment at time of injury (treatment group).

RESULTS

Histological analyses confirmed tendon thickening and collagen deposition after tendon injury and abrasion compared to control. Immunofluorescence showed higher levels of Col1 and α-SMA protein expression after injury compared to sham (*p<0.05). RT-qPCR also demonstrated increased gene expression of Col1 and α-SMA after injury compared to sham (*p<0.05). Gal3 protein expression also increased after injury and co-localized with α-SMA positive fibroblasts surrounding the fibrotic tendon. Gal3i treatment decreased collagen deposition and scarring observed in the treatment group (*p<0.05). Flow cytometry analysis further showed reduced numbers of profibrotic fibroblasts (CD26+) in the treatment compared to the control group (*p<0.05).

CONCLUSIONS

Our study provides a reproducible and reliable model to investigate tendon fibrosis. Findings suggest the potential of Gal3i to overcome fibrosis resulting from tendon injuries.

Piezo inhibition prevents and rescues scarring by targeting the adipocyte to fibroblast transition

While past studies have suggested that plasticity exists between dermal fibroblasts and adipocytes, it remains unknown whether fat actively contributes to fibrosis in scarring. We show that adipocytes convert to scar-forming fibroblasts in response to Piezo -mediated mechanosensing to drive wound fibrosis. We establish that mechanics alone are sufficient to drive adipocyte-to- fibroblast conversion. By leveraging clonal-lineage-tracing in combination with scRNA-seq, Visium, and CODEX, we define a "mechanically naïve" fibroblast-subpopulation that represents a transcriptionally intermediate state between adipocytes and scar-fibroblasts. Finally, we show that Piezo1 or Piezo2 -inhibition yields regenerative healing by preventing adipocytes' activation to fibroblasts, in both mouse-wounds and a novel human-xenograft-wound model. Importantly, Piezo1 -inhibition induced wound regeneration even in pre-existing established scars, a finding that suggests a role for adipocyte-to-fibroblast transition in wound remodeling, the least-understood phase of wound healing. Adipocyte-to-fibroblast transition may thus represent a therapeutic target for minimizing fibrosis via Piezo -inhibition in organs where fat contributes to fibrosis.

Multiplexed evaluation of mouse wound tissue using oligonucleotide barcoding with single-cell RNA sequencing

Despite its rapidly increased availability for the study of complex tissue, single-cell RNA sequencing remains prohibitively expensive for large studies. Here, we present a protocol using oligonucleotide barcoding for the tagging and pooling of multiple samples from healing wounds, which are among the most challenging tissue types for this application. We describe steps to generate skin wounds in mice, followed by tissue harvest and oligonucleotide barcoding. This protocol is also applicable to other species including rats, pigs, and humans. For complete details on the use and execution of this protocol, please refer to Stoeckius et al. (2018),1 Galiano et al. (2004),2 and Mascharak et al. (2022).3.

Beyond the Scar: A Basic Science Review of Wound Remodeling

Significance: Increasing development of experimental animal models has allowed for the study of scar formation. However, many pathophysiological unknowns remain in the longest stage of healing, the remodeling stage, which may continue for a year or more. The wound healing process results in different types of scarring classified as normal or pathological depending on failures at each stage. Failures can also occur during wound remodeling, but the molecular mechanisms driving the wound remodeling process have yet to be investigated. Recent Advances: While the current understanding of wound repair is based on investigations of acute healing, these experimental models have informed knowledge of key components of remodeling. This review examines the components that contribute to collagen organization and the final scar, including cell types, their regulation, and signaling pathways. Dysregulation in any one of these components causes pathologic healing. Critical Issues and Future Directions: As wounds continue to remodel months to years after reepithelialization, new models to better understand long-term remodeling will be critical for improving healing outcomes. Further investigation of the contributions of fibroblasts and cell signaling pathways involved during remodeling as well as their potential failures may inform new approaches in promoting regenerative healing beyond reepithelialization.

Exploring the Overlooked Roles and Mechanisms of Fibroblasts in the Foreign Body Response

Significance: Foreign body response (FBR), wherein a fibrotic capsule forms around an implanted structure, is a common surgical complication that often leads to pain, discomfort, and eventual revision surgeries. Although believed to have some mechanistic overlap with normal wound healing, much remains to be discovered about the specific mechanism by which this occurs. Recent Advances: Current understanding of FBR has focused on the roles of the immune system and the biomaterial, both major contributors to FBR. However, another key player, the fibroblast, is often overlooked. This review summarizes key contributors of FBR, focusing on the roles of fibroblasts. As much remains to be discovered about fibroblasts' specific roles in FBR, we draw on current knowledge of fibroblast subpopulations and functions during wound healing. We also provide an overview on candidate biomaterials and signaling pathways involved in FBR. Critical Issues and Future Directions: While the global implantable medical devices market is considerable and continues to appreciate in value, FBR remains one of the most common surgical implant complications. In parallel with the continued development of candidate biomaterials, further exploration of potential fibroblast subpopulations at a transcriptional level would provide key insights into further understanding the underlying mechanisms by which fibrous encapsulation occurs, and unveil novel directions for antifibrotic and regenerative therapies in the future.

Impact of family-centred postnatal training on maternal and neonatal health and care practices in district hospitals in two states in India: a pre-post study

BACKGROUND AND OBJECTIVES

The Care Companion Program (CCP) is an in-hospital multitopic skill-based training programme provided to families to improve postdischarge maternal and neonatal health. The states of Punjab and Karnataka in India piloted the programme in 12 district hospitals in July 2017, and no study to date has evaluated its impact.

METHODS

We compared telephonically self-reported maternal and neonatal care practices and health outcomes before and after the launch of the CCP programme in 11 facilities. Families in the preintervention group delivered between May to June 2017 (N=1474) while those in the intervention group delivered between August and October 2017 (N=3510). Programme effects were expressed as adjusted risk ratios obtained from logistic regression models.

RESULTS

At 2-week postdelivery, the practice of dry cord care improved by 4% (RR=1.04, 95% CI 1.02 to 1.06) and skin-to-skin care by 78% (RR=1.78, 95% CI 1.37 to 2.27) in the postintervention group as compared with preintervention group. Furthermore, newborn complications reduced by 16% (RR=0.84, 95% CI 0.76 to 0.91), mother complications by 12% (RR=0.88, 95% CI 0.79 to 0.97) and newborn readmissions by 56% (RR=0.44, 95% CI 0.31 to 0.61). Outpatient visits increased by 27% (RR=1.27, 95% CI 1.10 to 1.46). However, the practice of exclusive breastfeeding, unrestricted maternal diet, hand-hygiene and being instructed on warning signs were not statistically different.

CONCLUSION

Postnatal care should incorporate predischarge training of families. Our findings demonstrate that it is possible to improve maternal and neonatal care practices and outcomes through a family-centered programme integrated into public health facilities in low and middle-income countries.

Joint Preserving Treatments for Thumb CMC Arthritis

Trapezium resection with or without tendon suspension arthroplasty has been considered the gold standard surgical treatment for thumb carpometacarpal joint osteoarthritis (CMCJ OA). However, the removal of the trapezium may result in subsidence or shortening of the first metacarpal axis. Resection may also lead to reduced pinch strength and thumb instability. Joint preservation techniques may be used in early stages of CMCJ OA to promote pain relief, return to function, and delay more invasive procedures such as a trapezium resection.

Upper extremity necrotizing fasciitis in a Covid-19 patient

The novel COVID-19 virus has resulted in an immense burden in healthcare throughout the world. In addition to respiratory complications, COVID-19 has been associated with hypercoagulability and ischemic changes. We report a case of a patient with COVID-19 who presented with a rapidly progressing necrotizing fasciitis treated in our institution.

OUP accepted manuscript

Hypertrophic scar formation and non-healing wounds following Achilles tendon repair arise from poor vascularity to the incisional site or from excess mechanical stress/strain to the incision during the healing process. The embrace® scar therapy dressing is a tension offloading device for incisional scars. This study explored the effects of tension offloading during Achilles scar formation. A healthy 30-year-old male without any medical co-morbidities developed an acute rupture of his left Achilles tendon. The patient underwent open repair 1 week after injury. At post-operative day (POD) 14, the patient started daily tension offloading treatment on the inferior portion of the incision through POD 120. By POD 120, the untreated portion of the Achilles incision appeared hypertrophic and hyperpigmented, while the treated portion of the scar appeared flat with minimal pigmentation changes. The 12-week treatment of tension offloading on an Achilles tendon repair incision significantly improved cosmesis compared to untreated incision.

Trends in Leadership at Pediatric Orthopaedic Fellowships

BACKGROUND

Pediatric orthopaedic fellowship directors (FDs) have a valuable impact on the education of trainees and future leaders in the field. There is currently no research on the characteristics of pediatric orthopaedic FDs.

METHODS

Programs were identified using the Pediatric Orthopaedic Society of North America fellowship directory. Operative, nonoperative, and specialty programs were included. Data was collected through Qualtrics survey, e-mail, telephone, and online searches. Variables included demographics (age, sex, race/ethnicity), Hirsch index (h-index) as a measure of research productivity, graduate education, residency and fellowship training, years of hire at current institution and as FD, and leadership roles.

RESULTS

Fifty-five FDs were identified. The majority (49/55, 89%) were male and 77% (27/35) were Caucasian. The mean age at survey was 51.1±8.2 years. The mean h-index was 17.2. Older age correlated with higher h-index (r=0.48, P=0.0002). The average duration from fellowship graduation to FD appointment was 9.6±6.7 and 6.9±6.1 years from institutional hire. Sixteen FDs (29%) had additional graduate level degrees. Almost all (52/55, 95%) FDs completed orthopaedic surgery residencies and all graduated fellowship training. Twenty-nine percent (16/55) completed more than 1 fellowship. Most FDs (51/55, 93%) completed a fellowship in pediatric orthopaedic surgery. Ten FDs (18%) completed pediatric orthopaedic surgery fellowships that included spine-specific training. One-third of all current FDs were fellowship-trained at either Boston Children's Hospital (9/55, 16%) or Texas Scottish Rite Hospital for Children (9/55, 16%).

CONCLUSIONS

Pediatric orthopaedic FDs are typically early-career to mid-career when appointed, with a strong research background. Nearly a third completed additional graduate degrees or multiple fellowships. Although male dominated, there are more female FDs leading pediatric orthopaedic programs compared with adult reconstruction, trauma, and spine fellowships. As fellowships continue to grow and diversify, this research will provide a baseline to determine changes in FD leadership.

Trends in leadership at orthopaedic surgery sports medicine fellowships

BACKGROUND

Fellowship directors (FDs) in sports medicine influence the future of trainees in the field of orthopaedics. Understanding the characteristics these leaders share must be brought into focus. For all current sports medicine FDs, our group analyzed their demographic background, institutional training, and academic experience.

AIM

To serve as a framework for those aspiring to achieve this position in orthopaedics and also identify opportunities to improve the position.

METHODS

Fellowship programs were identified using both the American Orthopaedic Society for Sports Medicine and the Arthroscopy Association of North America Sports Medicine Fellowship Directories. The demographic and educational background data for each FD was gathered via author review of current curriculum vitae (CVs). Any information that was unavailable on CV review was gathered from institutional biographies, Scopus Web of Science, and emailed questionnaires. To ensure the collection of as many data points as possible, fellowship program coordinators, orthopaedic department offices and FDs were directly contacted via phone if there was no response via email. Demographic information of interest included: Age, gender, ethnicity, residency/fellowship training, residency/fellowship graduation year, year hired by current institution, time since training completion until FD appointment, length in FD role, status as a team physician and H-index.

RESULTS

Information was gathered for 82 FDs. Of these, 97.5% (n = 80) of the leadership were male; 84.15% (n = 69) were Caucasian, 7.32% (n = 6) were Asian-American, 2.44% (n = 2) were Hispanic and 2.44% (n = 2) were African American, and 3.66% (n = 3) were of another race or ethnicity. The mean age of current FDs was 56 years old (± 9.00 years), and the mean Scopus H-index was 23.49 (± 16.57). The mean calendar years for completion of residency and fellowship training were 1996 (± 15 years) and 1997 (± 9.51 years), respectively. The time since fellowship training completion until FD appointment was 9.77 years. 17.07% (n = 14) of FDs currently work at the same institution where they completed residency training; 21.95% (n = 18) of FDs work at the same institution where they completed fellowship training; and 6.10% (n = 5) work at the same institution where they completed both residency and fellowship training. Additionally, 69.5% (n = 57) are also team physicians at the professional and/or collegiate level. Of those that were found to currently serve as team physicians, 56.14% (n = 32) of them worked with professional sports teams, 29.82% (n = 17) with collegiate sports teams, and 14.04% (n = 8) with both professional and collegiate sports teams. Seven residency programs produced the greatest number of future FDs, included programs produced at least three future FDs. Seven fellowship programs produced the greatest number of future FDs, included programs produced at least four future FDs. Eight FDs (9.75%) completed two fellowships and three FDs (3.66%) finished three fellowships. Three FDs (3.66%) did not graduate from any fellowship training program. The Scopus H-indices for FDs are displayed as ranges that include 1 to 15 (31.71%, n = 26), 15 to 30 (34.15%, n = 28), 30 to 45 (20.73%, n = 17), 45 to 60 (6.10%, n = 5) and 60 to 80 (3.66%, n = 3). Specifically, the most impactful FD in research currently has a Scopus H-index value of 79. By comparison, the tenth most impactful FD in research had a Scopus H-index value of 43 (accessed December 1, 2019).

CONCLUSION

This study provides an overview of current sports medicine FDs within the United States and functions as a guide to direct initiatives to achieve diversity equality.

Recurrent and persistent carpal tunnel syndrome: "Triple-therapy approach"

Background

Various procedures have been described for patients undergoing a revision carpal tunnel release. These can include repeat open decompression with external or internal neurolysis, tenosynovectomy, endoscopic release, various flap techniques, saphenous vein wrapping and use of prosthetic implants. This study reports a case series of 30 consecutive patients who underwent revision carpal tunnel release at single institution from 2012 to 2018. Our surgical plan in all the patients involved a combination of these three techniques (triple therapy approach): neurolysis (external or internal) and tenosynovectomy, collagen matrix conduit wrap (NeuraWrap; Integra LifeSciences or Axoguard Nerve Protector, AxoGen Inc), and hypothenar fat flap.

Materials and methods

A total of 30 patient records were identified. The index surgery was performed by a variety of surgeons at varied private institutions as well as the VA hospital. However, all of the revision interventions in this series were performed by the senior author (Z.J.P.). Demographic data (age, sex, hand dominance, comorbidities, alcohol, and smoking history) were collected. Preoperative and postoperative symptoms were recorded for all patients, including: subjective outcomes, need for additional surgery and complications. Mean VAS preoperatively and postoperatively were compared using a paired t-test. All statistical analyses were performed with SPSS 20 (IBM, Chicago, IL).

Results

Patient reported measures of resolution of symptoms and VAS scores documented at 3 months. Of the 30 patients who underwent surgery for persistent or recurrent carpal tunnel syndrome, symptoms resolved completely in 25 patients. 2 patients were lost to follow up. 3 patients showed no improvement. The mean preoperative VAS score was 4.37 and declined to 1.23 after surgery (P < .0001).

Conclusion

Our study demonstrates that a combination of neurolysis and tenosynovectomy along with a nerve wrap and hypothenar fat flap should be considered in patients presenting with recurrent or persistent carpal tunnel syndrome.

Neisseria elongata osteomyelitis: Literature review and case report in a 63-year-old male presenting with progressive right-handed redness, swelling and pain

•

Neisseria elongata has unusual morphology among the Neisseria genus.

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The gram-negative rod is a causal organism of endocarditis and osteomyelitis.

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Early identification can inform treatment and prevent severe complications.

Introduction

Neisseria elongata, a gram-negative rod, has been identified in 23 cases of pathogenesis in the literature, of which only 2 were osteomyelitis. Here we report the third known case of isolated N. elongata cultures in a digital osteomyelitis.

Presentation of case

A 63-year-old male with peripheral vascular disease and lower extremity wounds presented to his vascular surgeon with right-handed redness and pain requiring urgent surgical intervention. Irrigation, debridement, and partial thumb amputation were performed, followed by treatment with a 6-week course of antibiotics.

Discussion

N. elongata is a rare cause of osteomyelitis and unfamiliarity with the causal organism and rod-like morphology may delay diagnosis and treatment.

Conclusion

Gram-negative coverage should be considered in high-risk populations with cellulitis to prevent progression to fulminant abscesses, suppurative tenosynovitis and osteomyelitis.

Social Media Presence Correlated with Improved Online Review Scores for Spine Surgeons

BACKGROUND

In the next decade, health care reimbursement will be more aligned to patient clinical outcomes. These outcomes are influenced by the patient's perceived opinion of his or her care. An evaluation into the role of surgeon demographics, social media (SM) accessibility, and office wait times was conducted to identify correlations with these among 3 online review platforms.

METHODS

A total of 206 (148 orthopedic, 58 neurosurgery trained) spine surgeons were included. Spine surgeon ratings and demographics data from 3 physician rating websites (Healthgrades.com [HG], Vitals.com, Google.com [G]) were collected in November 2019. Using the first 10 search results from G we then identified if the surgeons had publicly accessible Facebook, Twitter, or Instagram (IG) accounts.

RESULTS

The mean age of the cohort was 54.3 years (±9.40 years), and 28.2% had one form of publicly accessible SM. Having any SM was significantly correlated with higher scores on HG and G. An IG account was associated with significantly higher scores on all 3 platforms, and having a Facebook account correlated with significantly higher scores on HG in multivariate analysis. An office wait time between 16 and 30 minutes and >30 minutes was associated with worse scores on all 3 platforms (all P < 0.05). An academic practice was associated with higher scores on all 3 platforms (P < 0.05).

CONCLUSIONS

A shorter office wait time and an academic setting practice are associated with higher patient satisfaction scores on all 3 physician review websites. Accessible SM accounts are also associated with higher ratings on physician review websites, particularly IG.