Targeting lysosomal quality control as a therapeutic strategy against aging and diseases.

Previously, lysosomes were primarily referred to as the digestive organelles and recycling centers within cells. Recent discoveries have expanded the lysosomal functional scope and revealed their critical roles in nutrient sensing, epigenetic regulation, plasma membrane repair, lipid transport, ion homeostasis, and cellular stress response. Lysosomal dysfunction is also found to be associated with aging and several diseases. Therefore, function of macroautophagy, a lysosome-dependent intracellular degradation system, has been identified as one of the updated twelve hallmarks of aging. In this review, we begin by introducing the concept of lysosomal quality control (LQC), which is a cellular machinery that maintains the number, morphology, and function of lysosomes through different processes such as lysosomal biogenesis, reformation, fission, fusion, turnover, lysophagy, exocytosis, and membrane permeabilization and repair. Next, we summarize the results from studies reporting the association between LQC dysregulation and aging/various disorders. Subsequently, we explore the emerging therapeutic strategies that target distinct aspects of LQC for treating diseases and combatting aging. Lastly, we underscore the existing knowledge gap and propose potential avenues for future research.

Variations in deep iliac circumflex artery perforator chimeric flap design for single-stage customized-reconstruction of composite bone and soft-tissue defect.

BACKGROUND: The deep iliac circumflex artery (DICA) perforator (DICAP) chimeric flap is a valuable treatment strategy for single-stage reconstruction of composite bone and soft-tissue defects in upper and lower extremities. However, its utilization rate remains low owing to anatomical variations that lead to challenges when identifying and dissecting perforators. METHODS: A comprehensive anatomical investigation was conducted on the DICA system by injecting lead oxide into 12 fresh cadavers following a standardized procedure. From January 2008 to December 2020, 30 patients with composite bone and soft-tissue defects received reconstruction surgery with DICAP chimeric flap. One of the four specified surgical techniques was used to create a modified DICAP chimeric flap for the patients based on the size, shape, and location of the defect. RESULTS: Two branching patterns of DICA, transverse and ascending branches, were observed, and the former gave off the osteomusculocutaneous perforators and terminal musculocutaneous perforators. Thirty DICAP chimeric flaps were elevated successfully. The size of the skin paddles measured from 9 × 4.5 cm to 22 × 9 cm, and the bone components ranged from 3 × 2.5 × 1.5 cm to 6 × 3.5 × 2 cm. All flaps survived successfully after the operation, and all patients achieved primary closure of the donor sites. No patient encountered the fracture of transferred iliac segments. The mean bone union time was 5.5 months (ranging from 4 to 8 months). CONCLUSION: The DICA system is a suitable source for harvesting the DICAP chimeric flap to reconstruct composite bone and soft-tissue defects. It provides a flexible design for individualized coverage of such defects with limited donor-site morbidity.

Roles of Local Soluble Factors in Maintaining the Growth Plate: An Update.

The growth plate is a cartilaginous tissue found at the ends of growing long bones, which contributes to the lengthening of bones during development. This unique structure contains at least three distinctive layers, including resting, proliferative, and hypertrophic chondrocyte zones, maintained by a complex regulatory network. Due to its soft tissue nature, the growth plate is the most susceptible tissue of the growing skeleton to injury in childhood. Although most growth plate damage in fractures can heal, some damage can result in growth arrest or disorder, impairing leg length and resulting in deformity. In this review, we re-visit previously established knowledge about the regulatory network that maintains the growth plate and integrate current research displaying the most recent progress. Next, we highlight local secretary factors, such as Wnt, Indian hedgehog (Ihh), and parathyroid hormone-related peptide (PTHrP), and dissect their roles and interactions in maintaining cell function and phenotype in different zones. Lastly, we discuss future research topics that can further our understanding of this unique tissue. Given the unmet need to engineer the growth plate, we also discuss the potential of creating particular patterns of soluble factors and generating them in vitro.