Control Release of Adenosine Potentiate Osteogenic Differentiation within a Bone Integrative EGCG-g-NOCC/Collagen Composite Scaffold toward Guided Bone Regeneration in a Critical-Sized Calvarial Defect

Abstract

The regeneration of critical-sized bone defects with biomimetic scaffolds remains clinically challenging due to avascular necrosis, chronic inflammation, and altered osteogenic activity. Two confounding mechanisms, efficacy manipulation, and temporal regulation dictate the scaffold’s bone regenerative ability. Equally critical is the priming of the mesenchymal stromal cells (MSCs) toward lineage-specific differentiation into bone-forming osteoblast, which particularly depends on varied mechanochemical and biological cues during bone tissue regeneration. This study sought to design and develop an optimized osteogenic scaffold, adenosine/epigallocatechin gallate-N,O-carboxymethyl chitosan/collagen type I (AD/EGCG-g-NOCC@clgn I), having osteoinductive components toward swift bone regeneration in a calvarial defect BALB/c mice model. The ex vivo findings distinctly establish the pro-osteogenic potential of adenosine and EGCG, stimulating MSCs toward osteoblast differentiation with significantly increased expression of alkaline phosphatase, calcium deposits, and enhanced osteocalcin expression. Moreover, the 3D matrix recapitulates extracellular matrix (ECM) properties, provides a favorable microenvironment, structural support against mechanical stress, and acts as a reservoir for sustained release of osteoinductive molecules for cell differentiation, proliferation, and migration during matrix osteointegration observed. Evidence from in vivo experiments, micro-CT analyses, histology, and histomorphometry signify accelerated osteogenesis both qualitatively and quantitatively: effectual bone union with enhanced bone formation and new ossified tissue in 4 mm sized defects. Our results suggest that the optimized scaffold serves as an adjuvant to guide bone tissue regeneration in critical-sized calvarial defects with promising therapeutic efficacy.

Purinergic Signaling in Oral Tissues

“…Accordingly, other findings obtained by Verma et al [138] showed that an osteogenic scaffold comprising adenosine/epigallocatechin gallate-N,O-carboxymethyl chitosan/collagen type I (AD/EGCG-g-NOCC@clgn I), exhibited osteo-inductive properties in a calvarial defect model reproduced in BALB/c mice. The ex-vivo findings clearly established the proosteogenic potential of adenosine and EGCG, which both stimulated MSCs toward osteoblast differentiation as evaluated by the increased expression of selective osteogenic markers such as alkaline phosphatase and osteocalcin and enhanced calcium deposits.…”

Resorbable GBR Scaffolds in Oral and Maxillofacial Tissue Engineering: Design, Fabrication, and Applications

“…Bone healing is an intricate process involving a series of molecular and cellular events that are evolutionarily conserved [148]. In the realm of critical size bone injuries, two strategies are currently gaining prominence in clinical applications.…”

“…One approach focuses on utilizing scaffolds with bioresponsive elements, including osteoconductive and osteoinductive components, to stimulate the inherent cellular environment consisting of immune cells and stem/stromal progenitor cells. This stimulation aids in enhancing the healing and regeneration of bone [148]. The other approach revolves around in situ ectopic cellular reprogramming, achieved through the delivery of transcription and trophic factors, RNA-based therapies, manipulation of epigenetic factors using suitable biomaterials, and even in vivo gene editing [149].…”

“…The success of these innovative therapeutic approaches relies on the development of effective scaffolds that possess both strong osteogenic properties and high osteoinductive potential, with the ultimate goal of achieving clinical success. This approach offers an advantage over traditional autografts and allografts by eliminating the complications associated with donor sites [148]. Moreover, through a comprehensive comprehension and assessment of the factors implicated in the bone regeneration process, it becomes feasible to select suitable bioresponsive materials, whether derived from nature or synthesized, that closely emulate the bone microenvironment at the fracture site.…”

Recent advances on small molecules in osteogenic differentiation of stem cells and the underlying signaling pathways

“…Recently, a growing body of attention has been focused on adenosine and adenosine receptors as factors implicating in bone regeneration [ 28 ]. Exogenous adenosine supplementation is an effective method in order for successful osteogenic differentiation of mouse BMMSCs [ 71 ]. Also, administration of exogenous adenosine as a differentiation factor to cultured human ESCs has enhanced osteogenesis through A2b receptor adenosine signaling.…”