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Significance: Skin inevitably heals with the formation of a fibrotic scar. Patients affected by skin scarring suffer from long-term psychological and physical burdens. Recent Advances: Since the di...

As healthcare spending within the United States grows, payers have attempted to curb spending through higher cost sharing for patients. For families attempting to balance financial obligations with their children's surgical needs, high cost sharing could place families in difficult situations, deciding between life-altering surgery and bankruptcy. We aim to investigate trends in patient cost sharing and provider payments for cleft lip and palate repair.The IBM® MarketScan® Commercial Database was queried to extract patients younger than 18 years who underwent primary or secondary cleft lip and/or palate repair from 2007 to 2016. Financial variables included gross payments to the provider (facility and/or physician), net payment as reported by the carrier, coordination of benefits and other savings, and the beneficiary contribution, which consisted of patients' coinsurance, copay, and deductible payments. Linear regression was used to evaluate trends in payments over time. Poisson regression was used to trend the proportion of patients with a nonzero beneficiary contribution. All financial values were adjusted to 2016 dollars per the consumer price index to account for inflation.The sample included 6268 cleft lip and 9118 cleft palate repair episodes. Total provider payments increased significantly from 2007 to 2016 for patients undergoing cleft lip (median, $2527.33 vs $5116.30, P 0.008) and palate ($1766.13 vs $3511.70, P0.001) repair. Beneficiary contribution also increased significantly for both cleft lip ($155.75 vs $193.31, P0.001) and palate ($124.37 vs $183.22, P0.001) repair, driven by an increase in deductibles (P0.002). The proportion of cleft palate patients with a nonzero beneficiary contribution increased yearly by 1.6% (P = 0.002). Higher provider payments and beneficiary contributions were found in the Northeast (P0.001) and South (P0.011), respectively, for both cleft lip and palate repair.The US national data demonstrate that for commercially insured patients with cleft lip and/or palate, there has been a trend toward higher patient cost sharing, most pronounced in the South. This suggests that patients are bearing an increased cost burden while provider payments are simultaneously accelerating. Additional studies are needed to understand the impact of increased cost sharing on parents' decision to pursue cleft lip and/or palate repair for their children.

SummaryWhile 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 toPiezo-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 thatPiezo1orPiezo2-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 inpre-existingestablished 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 viaPiezo-inhibition in organs where fat contributes to fibrosis.

Striae distensae are common disfiguring cutaneous lesions but lack effective treatments because of an incomplete understanding of their pathophysiology. Dermal fibroblasts likely play an important role. The authors investigate the cellular-molecular features distinguishing fibroblasts from human striae distensae and normal skin. The authors also develop a mouse model of striae distensae.Human striae distensae and normal skin samples were compared for tensile strength and histologic structure. Fibroblasts from striae distensae and normal skin were isolated by fluorescence-activated cell sorting for gene expression analysis. Immunofluorescence staining and fluorescence-activated cell sorting were used to confirm gene expression data at the protein level. A mouse model of striae distensae formation was created by administering corticosteroids and mechanically loading the dorsal skin.Human striae distensae exhibited reduced tensile strength, more disordered collagen fibers, and epidermal atrophy compared to human normal skin. There were 296 up-regulated genes in striae distensae fibroblasts, including the profibrotic lineage and surface marker CD26. Up-regulated genes were involved in profibrotic and mechanoresponsive signaling pathways (TGFβ and FAK-PI3-AKT-signaling). In contrast, 571 genes were down-regulated, including CD74 and genes of the AMPK pathway. Increased CD26 and decreased CD74 expression was confirmed by fluorescence-activated cell sorting and immunofluorescence. Similar cutaneous histologic and gene expression changes were induced in hypercortisolemic mice by mechanically loading the dorsal skin.Fibroblasts from human striae distensae exhibit increased profibrotic and decreased antifibrotic signaling. CD26 and CD74 are promising surface markers that may be targeted therapeutically. The authors' mouse model of striae distensae can be used as a platform to test the efficacy of potential therapeutic agents.Striae distensae are common disfiguring cutaneous lesions whose etiology remains elusive, which has hindered development of effective treatment strategies. Dermal fibroblasts likely play an important role. The authors sought to elucidate the key cellular-molecular pathways distinguishing fibroblasts in striae distensae from those in normal skin.

Children undergoing cleft palate repair present challenges to postoperative management due to several factors that can complicate recovery. Utilization of multimodal analgesic protocols can improve outcomes in this population. We report experience designing and implementing an enhanced recovery after surgery (ERAS) pathway for cleft palate repair to optimize postoperative recovery.The primary aim was to implement an ERAS pathway with70% bundle adherence to achieve a 30% reduction in postoperative opioid consumption within 12 months. Our secondary aims assessed intraoperative opioid consumption, length of stay, timeliness of oral intake, and respiratory recovery.A multidisciplinary team of perioperative providers developed an ERAS pathway for cleft palate patients. Key drivers included patient and provider education, formal pathway creation and implementation, multimodal pain therapy, and target-based care. Interventions included maxillary nerve blockade and enhanced intra- and postoperative medication regimens. Outcomes were displayed as statistical process control charts.Pathway compliance was 77.0%. Patients during the intervention period (n = 39) experienced a 49% reduction in postoperative opioid consumption (p .0001) relative to our historical cohort (n = 63), with a mean difference of -0.33 ± 0.11 mg/kg (95% CI -0.55 to -0.12 mg/kg). Intraoperative opioid consumption was reduced by 36% (p = .002), with a mean difference of -0.27 ± 0.09 mg/kg (95% CI -0.45 to -0.09 mg/kg). Additionally, patients in the intervention group had a 45% reduction in time to first oral intake (p = .02) relative to our historical cohort, with a mean difference of -3.81 ± 1.56 h (95% CI -6.9 to -0.70). There was no difference in PACU or hospital length of stay, but there was a significant reduction in variance of all secondary outcomes.Opioid reduction and improved timeliness of oral intake is possible with an ERAS protocol for cleft palate repair, but our protocol did not alter PACU or hospital length of stay.

Objective: Epidermal CD34(+) stem cells located in the hair follicle (HF) bulge area are capable of inducing HF neogenesis and enhancing wound healing after transplantation. In this study, we observed CD34(+) cells derived from blood directly participate in dermal regeneration during full-thickness excisional wound healing. Approach: We isolated and in vitro expanded a subset of hematopoietic stem cell (HSC)-like precursor cells from the peripheral blood of adult mice with the surface markers: CD34(+), leucine rich repeat containing G protein-coupled receptor 5 (LGR5)(+), CD44(+), c-kit(+), lineage negative (lin(−)), and E-cadherin(−). These blood-derived precursor cells (BDPCs), can be further differentiated into epithelial-like cells (eBDPCs) and secret fibroblast growth factor 9 (Fgf9) protein. Result: When transplanted into full-thickness skin wounds, eBDPC treatment produced accelerated healing and enhanced skin structure regeneration with less dermal scar formation. Also, HF neogenesis (HFN) was observed with incorporation of labeled BDPCs in the wound area. Innovation: Nondermal-derived CD34(+) cells (BDPCs) from the adult unmobilized peripheral blood are capable of in vitro expansion and differentiation. Successful establishment of an in vitro technical platform for BDPCs expansion and differentiation. The in vitro expanded and differentiated epithelial-like cells (eBDPCs) enhance wound healing and directly contribute to skin regeneration and HFN. Conclusion: BDPCs isolated and expanded from adult peripheral blood may provide a possible new cell-based treatment strategy for HF neogenesis and skin wound regeneration.

BACKGROUND The purpose of this study was to evaluate the comparative incidence of obstructive sleep apnea following velopharyngeal insufficiency surgery in the United States. METHODS A retrospective analysis of cleft and noncleft pediatric patients who underwent velopharyngeal insufficiency surgery was performed using the IBM MarketScan Commercial Database. Patients were tracked longitudinally from 2007 to 2016 to evaluate the incidence of obstructive sleep apnea. Multivariable regression was used to evaluate predictors of postoperative obstructive sleep apnea and surgical revision. RESULTS A total of 1098 patients underwent a pharyngeal flap (61.0 percent), sphincter pharyngoplasty (22.2 percent), or palatal lengthening with or without island flaps (16.8 percent). Diagnoses were predominantly cleft lip and/or palate (52.8 percent) and congenital oropharyngeal anomalies (42.6 percent). Eighty patients (7.3 percent) developed obstructive sleep apnea at an average of 10.2 months postoperatively. Predictors of obstructive sleep apnea included older age (p = 0.014) and head and neck neoplasm (p = 0.011). The obstructive sleep apnea rate following sphincter pharyngoplasty was 11.1 percent, compared to 7.2 percent after pharyngeal flap surgery. Compared to sphincter pharyngoplasty, pharyngeal flap surgery was associated with a lower risk of further surgery (OR, 0.43; p = 0.010). Of patients with cleft lip and/or palate, 35 developed obstructive sleep apnea (6.0 percent) without a significant association with procedure type. CONCLUSIONS In this national claims database analysis of cleft and noncleft pediatric patients, the rate of obstructive sleep apnea following velopharyngeal insufficiency surgery was not significantly different for pharyngeal flap compared to sphincter pharyngoplasty. CLINICAL QUESTION/LEVEL OF EVIDENCE Therapeutic, III.

SUMMARY Striae distensae, or stretch marks, are common linear lesions of atrophic skin characterized histologically by epidermal atrophy, absent rete ridges, and alterations in connective tissue architecture. Hormonal excess, mechanical stress, and genetic predisposition are all associated with striae distensae, but their exact pathogenesis remains unknown. Despite a multitude of options, no single treatment has yet proven effective. In this article, the authors describe an up-to-date overview of striae distensae in terms of their etiology, pathophysiology, and therapeutic options. Further research is required to better elucidate their pathophysiology and to develop targeted effective treatments.

Objective: Mandibular distraction osteogenesis (MDO) is frequently performed to address airway obstruction in patients with Pierre Robin sequence (PRS), though more recently the technique of orthodontic airway plating (OAP) has gained traction. We aimed to evaluate OAP compared to MDO for airway obstruction in PRS. Design: A systematic literature search across PubMed, Embase, and Google Scholar identified all studies published in English, which involved MDO or any form of OAP as treatments for PRS. All relevant articles were reviewed in detail and reported on, adhering to PRISMA guidelines. Main Outcome Measures: Airway (tracheostomy avoidance, decannulation rate), feeding (full oral feeding tolerance). Results: Literature search identified 970 articles, of which 42 MDO studies and 9 OAP studies met criteria for review. A total of 1159 individuals were treated with MDO, and 322 individuals were treated with OAP. Primary outcomes appear similar for MDO and OAP at face value; however, this must be interpreted with different pretreatment contexts in mind. Conclusions: Orthodontic airway plating may be considered for airway obstruction in PRS, as some airway-related and feeding-related outcomes appear similar with MDO, per existing evidence in the literature. However, since PRS severity differed between studies, OAP cannot be uniformly considered a replacement for MDO. Further research is required to more comprehensively assess these treatment modalities inclusive of metrics that allow for direct comparison.

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

Objective The aim of this study was to determine the interaction of full thickness excisional wounds and tumors in vivo. Summary of background data Tumors have been described as wounds that do not heal due to similarities in stromal composition. On the basis of observations of slowed tumor growth after ulceration, we hypothesized that full thickness excisional wounds would inhibit tumor progression in vivo. Methods To determine the interaction of tumors and wounds, we developed a tumor xenograft/allograft (human head and neck squamous cell carcinoma SAS/mouse breast carcinoma 4T1) wound mouse model. We examined tumor growth with varying temporospatial placement of tumors and wounds or ischemic flap. In addition, we developed a tumor/wound parabiosis model to understand the ability of tumors and wounds to recruit circulating progenitor cells. Results Tumor growth inhibition by full thickness excisional wounds was dose-dependent, maintained by sequential wounding, and relative to distance. This effect was recapitulated by placement of an ischemic flap directly adjacent to a xenograft tumor. Using a parabiosis model, we demonstrated that a healing wound was able to recruit significantly more circulating progenitor cells than a growing tumor. Tumor inhibition by wound was unaffected by presence of an immune response in an immunocompetent model using a mammary carcinoma. Utilizing functional proteomics, we identified 100 proteins differentially expressed in tumors and wounds. Conclusion Full thickness excisional wounds have the ability to inhibit tumor growth in vivo. Further research may provide an exact mechanism for this remarkable finding and new advances in wound healing and tumor biology.

Background Aesthetic outcomes of unilateral cleft lip repairs have important psychosocial implications for patients who are heavily influenced by social perceptions. Online crowdsourcing offers the unique potential to efficiently recruit large numbers of laypeople to assess public perception. The aim of this study was to use the online crowdsourcing platform Mechanical Turk to compare the postoperative outcomes of Fisher, Millard, and Mohler cleft lip repair techniques. Methods Two hundred fifty-four participants were recruited through Mechanical Turk to evaluate 29 cropped and deidentified photographs of children, 8 photographs were controls without cleft lips and 21 were children with unilateral cleft lips who had undergone Fisher, Millard, or Mohler repairs (7 in each group). Respondents were asked whether a scar was present, whether they would be personally satisfied with the surgical result and used a Likert scale from 1 to 5 to rate overall appearance, scar severity, and nasal symmetry. Results Fewer respondents reported that a scar was present when assessing postoperative photographs of Fisher repairs (70.3 ± 8.6%) compared with Millard (92.0 ± 1.5%) or Mohler (88.8 ± 3.1%) repairs. Average rating of scar severity was also lower for Fisher (1.9) compared with Millard (2.6) or Mohler (2.6) repairs. Average ratings of nose symmetry, general appearance, and satisfaction with operative result were not statistically significantly different between the repair groups. Conclusions This study demonstrates the potential of online crowdsourcing to assess public perception of plastic surgery outcomes. The Mechanical Turk platform offers a reduction in selection bias, ease of study design, and enhanced efficiency of large-scale participant recruitment. Results indicate that the Fisher repair led to the most favored aesthetic outcomes compared with the Millard and Mohler techniques, particularly with regard to scar severity. Crowdsourcing is a powerful tool to assess layperson perception of plastic surgery outcomes and can be used to better guide surgical decision-making.

Objective Assess whether facial trauma wound care and antibiotic use recommendations are guided by evidence-based practice (EBP) or practice patterns, and investigate strategies to improve EBP adoption among surgical trainees. Design We conducted a survey of all trainees who manage facial trauma (general surgery, emergency medicine, plastic surgery, otolaryngology) to assess clinical knowledge and sources of treatment recommendations. Clinical questions were based on Oxford Center for Evidence-Based Medicine Level 1 or 2 evidence. We measured internal validity of questions using Cronbach's α. Results were weight-adjusted for nonresponse and then analyzed using Welch t test and descriptive statistics. Study Setting Stanford Hospital and Clinics, a Level I trauma center. Results Response rate was 50.3% overall (78/155). For recommendations on facial trauma wound and antibiotic use, nonspecialty junior residents most frequently relied on their own senior or specialty residents (79.1%); nonspecialty senior residents relied on specialty residents (67.9%). Specialty junior residents most often relied on their own senior residents (51.0%), the majority of whom made recommendations based on their own knowledge (73.2%). Questions assessing EBP knowledge had Cronbach's α of 0.98; response accuracy was similar between specialty and nonspecialty residents (54.6% vs 55.5%, p = 0.96). When provided recommendations that conflict with EBP, both nonspecialty and specialty residents more frequently followed recommendations rather than EBP; junior residents reported doing so to avoid conflict with superiors. Total 92.6% of surveyed residents felt cross-departmental EBP guidelines would improve patient care. Conclusions Facial trauma wound care and antibiotic recommendations disseminate down seniority and from craniofacial specialty to nonspecialty residents, yet knowledge of EBP among senior specialty and nonspecialty residents was weak. EBP may be difficult to adopt in the absence of consensus society guidelines. To address this gap, we published a review of EBP for facial trauma and plan to update our trauma manual with cross-departmental guidelines to facilitate EBP adoption among trainees.

Background:Acute wound healing is a dynamic process that results in the formation of scar tissue. The mechanisms of this process are not well understood; numerous signaling pathways are thought to play a major role. Here, the authors have identified β-catenin–dependent Wnt signaling as an early acut

Significance: Scarring of the skin from burns, surgery, and injury constitutes a major burden on the healthcare system. Patients affected by major scars, particularly children, suffer from long-term functional and psychological problems. Recent Advances: Scarring in humans is the end result of the wound healing process, which has evolved to rapidly repair injuries. Wound healing and scar formation are well described on the cellular and molecular levels, but truly effective molecular or cell-based antiscarring treatments still do not exist. Recent discoveries have clarified the role of skin stem cells and fibroblasts in the regeneration of injuries and formation of scar. Critical Issues: It will be important to show that new advances in the stem cell and fibroblast biology of scarring can be translated into therapies that prevent and reduce scarring in humans without major side effects. Future Directions: Novel therapies involving the use of purified human cells as well as agents that target specific cells...

Cutaneous wound repair is a highly coordinated cascade of cellular responses to injury which restores the epidermal integrity and its barrier functions. Even under optimal healing conditions, normal wound repair of adult human skin is imperfect and delayed healing and scarring are frequent occurrences. Dysregulated wound healing is a major concern for global healthcare, and, given the rise in diabetic and aging populations, this medicoeconomic disease burden will continue to rise. Therapies to reliably improve nonhealing wounds and reduce scarring are currently unavailable. Mesenchymal stromal cells (MSCs) have emerged as a powerful technique to improve skin wound healing. Their differentiation potential, ease of harvest, low immunogenicity, and integral role in native wound healing physiology make MSCs an attractive therapeutic remedy. MSCs promote cell migration, angiogenesis, epithelialization, and granulation tissue formation, which result in accelerated wound closure. MSCs encourage a regenerative, rather than fibrotic, wound healing microenvironment. Recent translational research efforts using modern bioengineering approaches have made progress in creating novel techniques for stromal cell delivery into healing wounds. This paper discusses experimental applications of various stromal cells to promote wound healing and discusses the novel methods used to increase MSC delivery and efficacy.

Background:Cleft palate repair is a challenging procedure for cleft surgeons to teach. A novel high-fidelity cleft palate simulator has been described for surgeon training. This study evaluates the simulator’s effect on surgeon procedural confidence and palatoplasty knowledge among learners.Methods

BACKGROUND Cell therapy with mesenchymal stromal cells is a promising strategy for tissue repair. Restoration of blood flow to ischemic tissues is a key step in wound repair, and mesenchymal stromal cells have been shown to be proangiogenic. Angiogenesis is critically regulated by the hypoxia-inducible factor (HIF) superfamily, consisting of transcription factors targeted for degradation by prolyl hydroxylase domain (PHD)-2. The aim of this study was to enhance the proangiogenic capability of mesenchymal stromal cells and to use these modified cells to promote wound healing. METHODS Mesenchymal stromal cells harvested from mouse bone marrow were transduced with short hairpin RNA (shRNA) against PHD-2; control cells were transduced with scrambled shRNA (shScramble) construct. Gene expression quantification, human umbilical vein endothelial cell tube formation assays, and wound healing assays were used to assess the effect of PHD knockdown mesenchymal stromal cells on wound healing dynamics. RESULTS PHD-2 knockdown mesenchymal stromal cells overexpressed HIF-1α and multiple angiogenic factors compared to control (p < 0.05). Human umbilical vein endothelial cells treated with conditioned medium from PHD-2 knockdown mesenchymal stromal cells exhibited increased formation of capillary-like structures and enhanced migration compared with human umbilical vein endothelial cells treated with conditioned medium from shScramble-transduced mesenchymal stromal cells (p < 0.05). Wounds treated with PHD-2 knockdown mesenchymal stromal cells healed at a significantly accelerated rate compared with wounds treated with shScramble mesenchymal stromal cells (p < 0.05). Histologic studies revealed increased blood vessel density and increased cellularity in the wounds treated with PHD-2 knockdown mesenchymal stromal cells (p < 0.05). CONCLUSIONS Silencing PHD-2 in mesenchymal stromal cells augments their proangiogenic potential in wound healing therapy. This effect appears to be mediated by overexpression of HIF family transcription factors and up-regulation of multiple downstream angiogenic factors.

Sanativo is an over-the-counter Brazilian product derived from Amazon rainforest plant extract that is purported to improve the healing of skin wounds. Two experimental studies have shown accelerated closure of nonsplinted excisional wounds in rat models. However, these models allow for significant contraction of the wound and do not approximate healing in the tight skin of humans.Full-thickness excisional wounds were created on the dorsal skin of mice and were splinted with silicone rings, a model that forces the wound to heal by granulation and reepithelialization. Sanativo or a control solution was applied either daily or every other day to the wounds. Photographs were taken every other day, and the degree of reepithelialization of the wounds was determined.With both daily and every-other-day applications, Sanativo delayed reepithelialization of the wounds. Average time to complete healing was faster with control solution versus Sanativo in the daily application group (9.4 versus 15.2 days; p0.0001) and the every-other-day application group (11 versus 13 days; p = 0.017). The size of visible scar at the last time point of the study was not significantly different between the groups, and no differences were found on histologic examination.Sanativo wound healing compound delayed wound reepithelialization in a mouse splinted excisional wound model that approximates human wound healing. The size of visible scar after complete healing was not improved with the application of Sanativo. These results should cast doubt on claims that this product can improve wound healing in humans.

Surgical manipulation of skin may result in undesired puckering of excess tissue, which is generally assumed to settle over time. In this article, the authors address the novel question of how this excess tissue remodels.Purse-string sutures (6-0 nylon) were placed at the midline dorsum of 22 wild-type BALB/c mice in a circular pattern marked with tattoo ink. Sutures were cinched and tied under tension in the treatment group, creating an excess tissue deformity, whereas control group sutures were tied without tension. After 2 or 4 weeks, sutures were removed. The area of tattooed skin was measured up to 56 days after suture removal. Histologic analysis was performed on samples harvested 14 days after suture removal.The majority of excess tissue deformities flattened within 2 days after suture removal. However, the sutured skin in the treatment group decreased in area by an average of 18 percent from baseline (n = 9), compared to a 1 percent increase in the control group (n = 10) at 14 days after suture removal (p0.05). This was similarly observed at 28 days (treatment, -11.7 percent; control, 4.5 percent; n = 5; p = 0.0243). Despite flattening, deformation with purse-string suture correlated with increased collagen content of skin, in addition to increased numbers of myofibroblasts. Change in area did not correlate with duration of suture placement.Excess dermal tissue deformities demonstrate the ability to remodel with gross flattening of the skin, increased collagen deposition, and incomplete reexpansion to baseline area. Further studies will reveal whether our findings in this mouse model translate to humans.

Wingless-related integration site (Wnt) signaling is an important regulator of bone development and regeneration. Wnts are short-range signaling molecules which act within the skeletal stem cell niche to influence cell proliferation and differentiation. Nineteen different Wnts have been identified in humans. Disruptions to Wnt signaling can lead to impairments in bone healing. Recent work has elucidated the complexities of Wnt signaling during bone development, repair, and regeneration, and highlighted its value as a potential therapeutic target for tissue regeneration. Here, we discuss the role of the canonical-Wnt-signaling pathway, its regulatory role in bone regeneration, and the recent clinical advance made towards its manipulation in regenerative medicine. This review contains 3 figures and 50 references. Keywords: osteogenesis, bone regeneration, bone remodeling, endochondral ossification, osteoblast, osteoprogenitor, lithium, fracture healing

Defects of the skeletal system are extremely common and amount to a significant biomedical burden. Bone is a unique tissue that retains its regenerative potential into adulthood. The biology behind bone development, repair, and regeneration is thus of considerable interest, and may lead to advances in patient care. There are two distinct forms of osteogenesis; bones of the craniofacial skeleton develop via intramembranous ossification, whilst bones of the appendicular skeleton form by endochondral ossification. In this review, bone regenerative mechanisms based on skeletal stem cell function during fracture repair and during distraction osteogenesis are reviewed. Skeletal stem cell function more closely follows developmental mechanisms during distraction osteogenesis compared to fracture osteogenesis. This review contains 5 figures and 50 references. Keywords: skeletal stem cell, osteogenesis, skeletogenesis, mechanotransduction, regeneration, remodeling, focal adhesion kinase, ossification

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

BACKGROUND: Recessive dystrophic epidermolysis bullosa (RDEB) patients have mutations in the COL7A1 gene and thus lack functional type VII collagen (C7) protein; they have marked skin fragility and blistering. This single-center phase 1/2a open-label study evaluated the long-term efficacy, safety, and patient-reported outcomes in RDEB patients treated with gene-corrected autologous cell therapy. METHODS: Autologous keratinocytes were isolated from participant skin biopsies. Epidermal sheets were prepared from cells transduced with a retrovirus carrying the full-length human COL7A1 gene. These gene-corrected autologous epidermal sheets measured 5 × 7 cm (35 cm(2)) and were transplanted onto 6 wound sites in each of 7 adult participants (n = 42 sites total) from 2013 to 2017. Participants were followed for 2 to 5 years. RESULTS: No participants experienced any serious related adverse events. Wound healing of 50% or greater by Investigator Global Assessment was present in 95% (36 of 38) of treated wounds versus 0% (0 of 6) of untreated control wounds at 6 months (P < 0.0001). At year 1, 68% (26 of 38) of treated wounds had 50% or greater healing compared with 17% (1 of 6) of control wounds (P = 0.025). At year 2, 71% (27 of 38) of treated wounds had 50% or greater healing compared with 17% (1 of 6) of control wounds (P = 0.019). CONCLUSION: C7 expression persisted up to 2 years after treatment in 2 participants. Treated wounds with 50% or greater healing demonstrated improvement in patient-reported pain, itch, and wound durability. This study provides additional data to support the clinically meaningful benefit of treating chronic RDEB wounds with ex vivo, C7 gene–corrected autologous cell therapy. This approach was safe and promoted wound healing that was associated with improved patient-reported outcomes. TRIAL REGISTRATION: Clinicaltrials.gov identifier: NCT01263379. FUNDING: Epidermolysis Bullosa Research Partnership, Epidermolysis Bullosa Medical Research Foundation, NIH R01 AR055914, Office of Research and Development at the Palo Alto Veteran’s Affairs Medical Center, and the Dermatology Foundation.

The iliac crest and ribs are valuable sites for harvesting bone that can be used in a variety of plastic and reconstructive operations. Bone from the iliac crest is most commonly harvested through an open approach, but it can also be harvested through a percutaneous approach. The open approach offers cortical and cancellous bone, whereas the percutaneous approach yields only cancellous bone. Full-thickness bone from the ribs can also be harvested safely and efficiently. This chapter describes the techniques for these procedures, the tools routinely used, and common pitfalls and complications that the plastic surgeon must be aware of.

Pediatric facial fracture management is often complex and demanding. The structure and topography of the pediatric craniofacial skeleton are profoundly different from the mature skull. Consequently, the pediatric facial skeleton responds differently to traumatic force. Although the incidence of pediatric facial trauma is higher than in the adult population, the incidence of facial fracture is significantly lower. The management in younger patients is often more conservative because of potential growth impairment. As the facial skeleton matures, more conventional surgical approaches become appropriate. This review provides an understanding of the unique elements of facial fracture management in the pediatric population.

Adult cutaneous wounds repair through a fibroproliferative response which results in a scar. Early-gestation fetal skin has the ability to regenerate damaged skin without the formation of a scar in a process that resembles regeneration. The fetal and adult wound healing phenotypes are characterized by differences in the degree of inflammation, molecular signaling, extracellular matrix composition, and biomechanical properties. Significant advancements in understanding scarless fetal mammalian wound healing have led to the development of therapeutic applications with the potential to reduce scarring in the healing of adult cutaneous wounds. This chapter outlines the molecular and cellular processes involved in scarless fetal wound healing and the progress that has been made in recapitulating this process in adult wounds.

From the moment we are born, every injury to the skin has the potential to form a scar, many of which can impair form and/or function. As such, scar management constitutes a billion-dollar industry. However, effectively promoting scarless wound healing remains an elusive goal. The complex interactions of wound healing contribute to our inability to recapitulate scarless wound repair as it occurs in nature, such as in fetal skin and the oral mucosa. However, many new advances have occurred in recent years, some of which have translated scientific findings from bench to bedside. In vivo lineage tracing has helped establish a variety of novel cellular culprits that may act as key drivers of the fibrotic response. These newly characterized cell populations present further targets for therapeutic intervention, some of which have previously demonstrated promising results in animal models. Here, we discuss several recent studies that identify exciting approaches for diminishing scar formation. Particular attention will also be paid to the canonical Wnt/β-catenin signaling pathway, which plays an important role in both embryogenesis and tissue repair. New insights into the differential effects of Wnt signaling on heterogeneous fibroblast and keratinocyte populations within the skin further demonstrate methods by which wound healing can be re-directed to a more fetal scarless phenotype. Graphical abstract Recent approaches to reducing scar formation. Representation showing novel scientific approaches for decreasing scar formation, including the targeting of pro-fibrotic cell populations based on surface molecule expression (e.g. DPP4(+) fibroblasts, ADAM12(+) pericytes). Modulation of cellular mechanotransduction pathways are another means to reduce scar formation, both at the molecular level or, macroscopically with dressings designed to offload tension, at cutaneous wound sites (ADAM12 a disintegrin and metalloprotease 12, DPP4 dipeptidyl peptidase-4, FAK focal adhesion kinase).

A new group of blood-derived CD34+ progenitor cells (BDPCs) with the ability to expand and differentiate into functional hepatocyte-like cells and promote liver regeneration is reported. With their ease of access, application through the peripheral blood, and the capability of rapid expansion and hepatic differentiation, BDPCs have great potential as a cell-based therapy for liver disease., The low availability of functional hepatocytes has been an unmet demand for basic scientific research, new drug development, and cell-based clinical applications for decades. Because of the inability to expand hepatocytes in vitro, alternative sources of hepatocytes are a focus of liver regenerative medicine. We report a new group of blood-derived CD34+ progenitor cells (BDPCs) that have the ability to expand and differentiate into functional hepatocyte-like cells and promote liver regeneration. BDPCs were obtained from the peripheral blood of an adult mouse with expression of surface markers CD34, CD45, Sca-1, c-kit, and Thy1.1. BDPCs can proliferate in vitro and differentiate into hepatocyte-like cells expressing hepatocyte markers, including CK8, CK18, CK19, α-fetoprotein, integrin-β1, and A6. The differentiated BDPCs (dBDPCs) also display liver-specific functional activities, such as glycogen storage, urea production, and albumin secretion. dBDPCs have cytochrome P450 activity and express specific hepatic transcription factors, such as hepatic nuclear factor 1α. To demonstrate liver regenerative activity, dBDPCs were injected into mice with severe acute liver damage caused by a high-dose injection of carbon tetrachloride (CCl4). dBDPC treatment rescued the mice from severe acute liver injury, increased survival, and induced liver regeneration. Because of their ease of access and application through peripheral blood and their capability of rapid expansion and hepatic differentiation, BDPCs have great potential as a cell-based therapy for liver disease. Significance Hematopoietic stem/progenitor cell expansion and tissue-specific differentiation in vitro are challenges in regenerative medicine, although stem cell therapy has raised hope for the treatment of liver diseases by overcoming the scarcity of hepatocytes. This study identified and characterized a group of blood-derived progenitor cells (BDPCs) from the peripheral blood of an adult mouse. The CD34+ progenitor-dominant BDPCs were rapidly expanded and hepatically differentiated into functional hepatocyte-like cells with our established coculture system. BDPC treatment increased animal survival and produced full regeneration in a severe liver injury mouse model caused by CCl4. BDPCs could have potential for liver cell therapies.