A GelMA/polydopamine hydrogel with PTH and osteogenically stimulated alveolar mucosa-derived stem cells promotes bone regeneration in MRONJ-affected wounds

Abstract

Background Medication-related osteonecrosis of the jaw (MRONJ) is a serious complication in patients taking bisphosphonates. This study aimed at developing a mesenchymal stem cell-based strategy to reduce the incidence of MRONJ and recover regeneration capability of MRONJ-affected wounds by using a gelatin methacryloyl/polydopamine hydrogel (GelMA/PD) to adhere alveolar mucosa-derived stem cells (AMCs) on the bone surface, with the osteogenically stimulated AMCs modulated by microRNA (miR) transfection, and the osteoanabolic environment activated by parathyroid hormone (PTH). Methods GelMA/PD was synthesized by photo-crosslinking, and the incorporation of PD onto GelMA as well as mechanical properties were assessed. Rat AMCs were isolated, and the stemness was characterized. AMCs were osteogenically stimulated by miR transfection. Maxillary osteotomy was created in rats administrated with zoledronic acid and dexamethasone to simulate MRONJ-affected wounds, and osteotomy in rats without ZA served as healthy controls. Wounds were unfilled or filled with GelMA/PD alone, GelMA/PD with AMCs (GA), GelMA/PD with OAMCs (GO), or GelMA/PD with OAMCs and PTH (PO), and were assessed by gross observation, micro-CT imaging, histology, and immunohistochemistry for osteoblast-osteoclast coupling. Results GelMA/PD exhibited modestly decreased compressive strength and superior adhesion strength compared with GelMA. AMCs were double positive for CD73 and CD90, showed trilineage differentiation capability, and were osteogenically stimulated by miR-218 transfection. Among MRONJ-affected wounds, soft tissue coverage was accelerated, with reduced sequestra and significantly greater bone volume in PO group (38.46 ± 10.02%) relative to unfilled group (21.81 ± 6.18%), and osteoblast-osteoclast coupling was evident in GO and PO groups. Soft tissue recovery, inflammation reduction, and matrix deposition on defect surfaces were more prominent in PO group.

1. Introduction

Medication-related osteonecrosis of the jaw (MRONJ), as defined by the American Association of Oral and Maxillofacial Surgeons, refers to the condition of necrotic bone exposure in the maxillofacial region for more than 8 weeks in patients taking antiresorptive agents such as bisphosphonates (BP) or antiangiogenic agents without histories of radiation therapy or metastatic diseases involving the jaw [1]. A systematic review revealed that MRONJ developed in 1–3% of cancer patients treated with antiresorptive or antiangiogenic agents and in 0–0.2% of osteoporotic patients treated with antiresorptive agents [2]. Although the mechanisms leading to the onset of MRONJ are not fully understood, the suppression of osteoclastogenesis to affect bone turnover forms a major hypothesis for MRONJ induction in BP-treated patients [3].

Invasive dentoalveolar operation, specifically tooth extraction, is the most common predisposing factor to trigger MRONJ in patients taking oral BP [4]. Because inhibited mucosal healing following invasive dental procedures is a frequent clinical manifestation of MRONJ, infection and inflammation elicited by bacterial deposits on an opened dental wound also causes sequestra formation [5, 6]. To prevent the onset of MRONJ, minimally traumatic techniques and mucosal wound closure have been suggested for invasive dental operations in patients taking BP [7]. Adjunctive treatments such as hyperbaric oxygen, platelet-rich plasma, and low-level laser therapy have been proposed for preventing or treating MRONJ [8]. However, the efficiency and predictability of these therapies is yet to be identified.

Mesenchymal stem cell (MSC)-based treatment strategies have shown effectiveness in treating MRONJ in vivo, and allogenic MSCs are preferred because the viability and stemness of MSCs is impaired in BP-treated patients [9]. Oral mucosa-derived MSCs seem an ideal solution for preventing the onset of MRONJ based on their abundance and accessibility. A previous investigation revealed that alveolar mucosa-derived stem cells (AMCs) are multipotent with low antigenicity, and allogenic AMCs can promote the healing of extraction sockets and osseous repair in the craniofacial region [10]. Studies on how AMCs modulate MRONJ-affected wounds are still lacking. MicroRNAs (miRs) act as regulators of gene expression and have emerged as powerful tools to direct stem cell fate, offering a promising approach to enhance the osteogenic potential of MSCs for regenerative applications.