Do nonsteroidal anti-inflammatory drugs impair tissue healing?

Wound healing dynamics, morbidity, and complications of palatal soft-tissue harvesting

Palatal-tissue harvesting is a routinely performed procedure in periodontal and peri-implant plastic surgery. Over the years, several surgical approaches have been attempted with the aim of obtaining autogenous soft-tissue grafts while minimizing patient morbidity, which is considered the most common drawback of palatal harvesting. At the same time, treatment errors during the procedure may increase not only postoperative discomfort or pain but also the risk of developing other complications, such as injury to the greater palatine artery, prolonged bleeding, wound/flap sloughing, necrosis, infection, and inadequate graft size or quality. This chapter described treatment errors and complications of palatal harvesting techniques, together with approaches for reducing patient morbidity and accelerating donor site wound healing. The role of biologic agents, photobiomodulation therapy, local and systemic factors, and genes implicated in palatal wound healing are also discussed.

Mechanoresponsive regulation of fibroblast-to-myofibroblast transition in three-dimensional tissue analogues: mechanical strain amplitude dependency of fibrosis

The spatiotemporal interaction and constant iterative feedback between fibroblasts, extracellular matrix, and environmental cues are central for investigating the fibroblast-induced musculoskeletal tissue regeneration and fibroblast-to-myofibroblast transition (FMT). In this study, we created a fibroblast-laden 3D tissue analogue to study (1) how mechanical loading exerted on three-dimensional (3D) tissues affected the residing fibroblast phenotype and (2) to identify the ideal mechanical strain amplitude for promoting tissue regeneration without initiating myofibroblast differentiation. We applied uniaxial tensile strain (0, 4, 8, and 12%) to the cell-laden 3D tissue analogues to understand the interrelation between the degree of applied mechanical loading amplitudes and FMT. Our data demonstrated that 4% mechanical strain created an anabolic effect toward tissue regeneration, but higher strain amplitudes over-stimulated the cells and initiated fibrotic tissue formation. Under increased mechanical strain amplitudes, fibroblasts were activated from a homeostatic state to a proto-myofibroblast state which resulted in increased cellularity accompanied by increased expressions of extracellular matrix (ECM) components, activation stressors (TGF-β1 and TGF-βR1), and profibrotic markers. This further transformed fibroblasts into α-smooth muscle actin expressing myofibroblasts. Understanding the interplay between the applied degree of mechanical loading exerted on 3D tissues and residing fibroblast phenotypic response is important to identify specific mechanomodulatory approaches for tissue regeneration and the informed mechanotherapy-guided tissue healing strategies.

Myeloid ALX/FPR2 regulates vascularization following tissue injury

Ischemic injury initiates a sterile inflammatory response that ultimately participates in the repair and recovery of tissue perfusion. Macrophages are required for perfusion recovery during ischemia, in part because they produce growth factors that aid in vascular remodeling. The input signals governing this pro-revascularization phenotype remain of interest. Here we found that hindlimb ischemia increases levels of resolvin D1 (RvD1), an inflammation-resolving lipid mediator that targets macrophages via its receptor, ALX/FPR2. Exogenous RvD1 enhances perfusion recovery during ischemia, and mice deficient in Alx/Fpr2 have an endogenous defect in this process. Mechanistically, RNA sequencing revealed that RvD1 induces a transcriptional program in macrophages characteristic of a pro-revascularization phenotype. Vascularization of ischemic skeletal muscle, as well as cutaneous wounds, is impaired in mice with myeloid-specific deficiency of Alx/Fpr2, and this is associated with altered expression of pro-revascularization genes in skeletal muscle and macrophages isolated from skeletal muscle. Collectively, these results uncover a role of ALX/FPR2 in revascularization that may be amenable to therapeutic targeting in diseases associated with altered tissue perfusion and repair.