Osteogenic Potential of Mesenchymal Stem Cells on Expanded Polytetrafluoroethylene Coated with Both a Poly-Amino-Acid Urethane Copolymer and Collagen

Prevention of bisphosphonate-related osteonecrosis of the jaw with basic fibroblast growth factor: an experimental study in rats

Bisphosphonate-related osteonecrosis of the jaw (BRONJ), characterized by persistent jaw bone exposure, is believed to result from the inhibition of bone remodeling and wound healing, often associated with potent intravenous bisphosphonates such as zoledronic acid (ZA). These bisphosphonates are known to significantly impact the healing of soft and bone tissues due to their anti-angiogenic properties. Our study aimed to explore whether applying the basic fibroblast growth factor (bFGF), known for its ability to promote angiogenesis and bone remodeling, over extraction sockets could prevent the onset of BRONJ in rats administered with ZA. The experimental protocol involved administering each rat with two intravenous injections of 60 μg/kg of ZA, followed by tooth extraction. Rats were then divided into two groups: the test group (n = 12), which had a mixture of 3% hydroxypropyl cellulose (HPC) and 0.3% bFGF applied over their extraction sockets, and the control group (n = 12), which received only a 3% HPC application. Wound healing was monitored for 8 weeks post-extraction and assessed using micro-computed tomography, histological evaluations, and immunohistochemical analysis of CD31- and CD105-positive vessels. Results showed a BRONJ incidence rate of 100% (12/12) in the control group, whereas the rate was significantly lower in the test group at 8.3% (1/12). Furthermore, the test group demonstrated marked increases in both angiogenesis and new bone formation. Our findings suggest that the local application of bFGF might serve as an effective therapeutic approach to prevent the onset of BRONJ following tooth extraction in patients receiving bisphosphonate therapy.

Impact of beta-tricalcium phosphate on preventing tooth extraction-triggered bisphosphonate-related osteonecrosis of the jaw in rats

Antiresorptive or antiangiogenic drugs can cause medication-related osteonecrosis of the jaw that is refractory. Bisphosphonate-related osteonecrosis of the jaw (BRONJ) may be caused by procedures such as tooth extraction damage the alveolar bone, release bisphosphonates (BPs) and impede healing. This study investigated strategies for BRONJ prevention and molecular mechanisms of its onset. We assessed the effectiveness of filling extraction sockets with beta-tricalcium phosphate (β-TCP). Rats were administered zoledronic acid (ZA) 1.2 mg/kg once per week for 2 weeks, and a molar was extracted. They were randomly assigned to the β-TCP group (bone defects filled with 0.01 g of β-TCP) or control group. Tissue content measurements indicated 2.2 ng of ZA per socket in the β-TCP group and 4.9 ng in the control group, confirming BP distribution and BP adsorption by β-TCP in vivo. At 4 weeks after extraction, the β-TCP group had normal mucosal coverage without inflammation. Moreover, at 8 weeks after extraction, enhanced bone healing, socket coverage, and new bone formation were observed in the β-TCP group. Connective tissue in the extraction sockets suggested that local increases in BP concentrations may suppress the local autophagy mechanisms involved in BRONJ. Filling extraction sockets with β-TCP may prevent BRONJ.

Biomineral/Agarose Composite Gels Enhance Proliferation of Mesenchymal Stem Cells with Osteogenic Capability

Hydroxyapatite (HA) or calcium carbonate (CaCO₃) formed on an organic polymer of agarose gel is a biomaterial that can be used for bone tissue regeneration. However, in critical bone defects, the regeneration capability of these materials is limited. Mesenchymal stem cells (MSCs) are multipotent cells that can differentiate into bone forming osteoblasts. In this study, we loaded MSCs on HA- or CaCO₃-formed agarose gel and cultured them with dexamethasone, which triggers the osteogenic differentiation of MSCs. High alkaline phosphatase activity was detected on both the HA- and CaCO₃-formed agarose gels; however, basal activity was only detected on bare agarose gel. Bone-specific osteocalcin content was detected on CaCO₃-formed agarose gel on Day 14 of culture, and levels subsequently increased over time. Similar osteocalcin content was detected on HA-formed agarose on Day 21 and levels increased on Day 28. In contrast, only small amounts of osteocalcin were found on bare agarose gel. Consequently, osteogenic capability of MSCs was enhanced on CaCO₃-formed agarose at an early stage, and both HA- and CaCO₃-formed agarose gels well supported the capability at a later stage. Therefore, MSCs loaded on either HA- or CaCO₃-formed agarose could potentially be employed for the repair of critical bone defects.

Cell based advanced therapeutic medicinal products for bone repair: Keep it simple?

The development of cell based advanced therapeutic medicinal products (ATMPs) for bone repair has been expected to revolutionize the health care system for the clinical treatment of bone defects. Despite this great promise, the clinical outcomes of the few cell based ATMPs that have been translated into clinical treatments have been far from impressive. In part, the clinical outcomes have been hampered because of the simplicity of the first wave of products. In response the field has set-out and amassed a plethora of complexities to alleviate the simplicity induced limitations. Many of these potential second wave products have remained "stuck" in the development pipeline. This is due to a number of reasons including the lack of a regulatory framework that has been evolving in the last years and the shortage of enabling technologies for industrial manufacturing to deal with these novel complexities. In this review, we reflect on the current ATMPs and give special attention to novel approaches that are able to provide complexity to ATMPs in a straightforward manner. Moreover, we discuss the potential tools able to produce or predict 'goldilocks' ATMPs, which are neither too simple nor too complex.