Decellularized diaphragmatic muscle drives a constructive angiogenic response in vivo

Skeletal muscle tissue engineering (TE) aims to efficiently repair large congenital and acquired defects. Biological acellular scaffolds are considered a good tool for TE, as decellularization allows structural preservation of tissue extracellular matrix (ECM) and conservation of its unique cytokine reservoir and the ability to support angiogenesis, cell viability, and proliferation. This represents a major advantage compared to synthetic scaffolds, which can acquire these features only after modification and show limited biocompatibility. In this work, we describe the ability of a skeletal muscle acellular scaffold to promote vascularization both ex vivo and in vivo. Specifically, chicken chorioallantoic membrane assay and protein array confirmed the presence of pro-angiogenic molecules in the decellularized tissue such as HGF, VEGF, and SDF-1\u3b1. The acellular muscle was implanted in BL6/J mice both subcutaneously and ortotopically. In the first condition, the ECM-derived scaffold appeared vascularized 7 days post-implantation. When the decellularized diaphragm was ortotopically applied, newly formed blood vessels containing CD31+, \u3b1SMA+, and vWF+ cells were visible inside the scaffold. Systemic injection of Evans Blue proved function and perfusion of the new vessels, underlying a tissue-regenerative activation. On the contrary, the implantation of a synthetic matrix made of polytetrafluoroethylene used as control was only surrounded by vWF+ cells, with no cell migration inside the scaffold and clear foreign body reaction (giant cells were visible). The molecular profile and the analysis of macrophages confirmed the tendency of the synthetic scaffold to enhance inflammation instead of regeneration. In conclusion, we identified the angiogenic potential of a skeletal muscle-derived acellular scaffold and the pro-regenerative environment activated in vivo, showing clear evidence that the decellularized diaphragm is a suitable candidate for skeletal muscle tissue engineering and regeneration

Hirschsprung's disease and Down syndrome: From the reappraisal of risk factors to the impact of surgery

Introduction: The association of Hirschsprung disease (HSCR) and Down Syndrome (DS) is not uncommon (HSCR + DS). This paper aims at reporting the results of a 24-year series focusing on surgical approach, complications and long term outcome. Materials and methods: The notes of all patients admitted with a diagnosis of HSCR + DS have been retrospectively reviewed. Surgical details, intraoperative complications, long term issues and functional outcome have been recorded. The results have been compared to those of patients without DS and were assessed based on surgical approach. Results: A total of 23 HSCR + DS out of a series of 385 HSCR (6%) have been included. Preoperative enterocolitis (HAEC) was reported by 32%. Associated anomalies were detected in more than half of the patients. In particular, Congenital Heart Defects (CHDs) were reported by 57%. Postoperative complications (mostly symptomatic anal sphincter achalasia) were experienced by 55%. Constipation was experienced by 30%; severe continence issues, by 53%. One patient suffering from severe CHDs died. With regard to complications, only symptomatic anal achalasia requiring intrasphincteric BoTox injection was significantly more frequent in HSCR + DS (30% vs 10%, p = 0.0071). Similarly, continence proved to be significantly worse in HSCR + DS. Discussion: With the exception of symptomatic anal achalasia, HSCR + DS patients proved not to have a higher likelihood of complications compared to HSCR alone. On the other hand, functional results in the long term are worse. As a consequence, long term follow up and personalized rehabilitation programs are warranted for this delicate subset of HSCR patients. Level of evidence: Level III