Bone Tissue Engineering Strategies for Alveolar Cleft: Review of Preclinical Results and Guidelines for Future Studies

The Skin-to-Mucosa Ratio Defines the Osteogenic Potential of Lip Fibroblasts

Fibroblasts isolated from discarded lip tissue obtained during cheiloplasty in patients with cleft lip/palate (CLP) show promising osteogenic potential and may be an appealing cell source for autologous bone regeneration. As the lip is a mucocutaneous junction, explant cultures from unseparated lip biopsies produce mesenchymal outgrowths composed of skin- and mucosa-derived fibroblasts. The proportions of the 2 fibroblast populations, however, differ among CLP patients and depend on the morphology of the excised sample, which is unique for each donor. Understanding the osteogenic activities of CLP fibroblast populations with varying skin-to-mucosa ratios is critical for their therapeutic application. We isolated CLP fibroblasts from 10 unseparated lip biopsies and comprehensively evaluated them for their bone differentiation capacities in vitro, demonstrating heterogeneous osteogenic potentials. Because there are no markers that can distinguish skin from mucosa fibroblasts, we used the respective and matching CLP keratinocytes to ascertain the skin-to-mucosa ratio of the 10 specimens. Thus, we found that CLP fibroblasts isolated from biopsies with high skin-to-mucosa ratios had a much higher osteogenic capacity than those derived from biopsies with low skin-to-mucosa ratios. To validate and solidify these findings, we carefully separated skin and mucosa tissues during corrective lip surgery to isolate pure skin and mucosa CLP lip fibroblasts. Indeed, skin had a higher osteogenic potential than their mucosal counterparts did. Furthermore, we discovered that the high osteogenic activity in skin was limited to specific subpopulations of yet unknown identities. Our findings indicate that skin fibroblasts perform better than their mucosal counterparts do, even though both types of fibroblasts can differentiate into bone-forming cells.

Failure Rates Based on Alveolar Cleft Volume: Analysis of the Critical-Size Defect for Alveolar Bone Grafting

BACKGROUND

Alveolar bone grafting (ABG) using iliac crest bone graft (ICBG) is the best practice for children with complete cleft lip and palate. With the advent of recombinant human bone morphogenetic protein (rhBMP-2) and demineralized bone matrix (DBM), excellent results can be achieved while avoiding donor-site morbidity. This study aimed to determine critical-size defects by analyzing graft failure rates for ICBG and rhBMP-2/DBM to guide surgeons performing ABG.

METHODS

A retrospective review was conducted evaluating patients who underwent ABG from 2016 through 2022. Patients with preoperative and postoperative cone beam computed tomography (CBCT) imaging were included. Volumetric defect sizes were calculated using preoperative imaging. Graft success criteria were based on both clinical and radiographic outcomes. Logistic regressions analyzed graft failure rates to identify an optimal cutoff, which defined the critical-size defect.

RESULTS

A total of 93 patients were included. Bone graft cohorts included ICBG ( n = 30) and rhBMP-2/DBM ( n = 63). The critical-size defects were calculated to be 810 mm 3 and 885 mm 3 for ICBG and rhBMP-2/DBM, respectively. There were significantly higher graft failure rates beyond the critical size compared with below for both ICBG (71.4% versus 0.0%; P < 0.001) and rhBMP-2/DBM (65.0% versus 14.0%; P < 0.001).

CONCLUSIONS

This study identified critical-size defects based on alveolar cleft volume for ICBG or rhBMP-2/DBM with higher graft failure rates beyond the predicted thresholds. Distinct ranges in cleft volume were identified where patients might benefit from each select graft option.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, III.

Effect of Dimethyloxalylglycine on Stem Cells Osteogenic Differentiation and Bone Tissue Regeneration-A Systematic Review

Dimethyloxalylglycine (DMOG) has been found to stimulate osteogenesis and angiogenesis of stem cells, promoting neo-angiogenesis in bone tissue regeneration. In this review, we conducted a comprehensive search of the literature to investigate the effects of DMOG on osteogenesis and bone regeneration. We screened the studies based on specific inclusion criteria and extracted relevant information from both in vitro and in vivo experiments. The risk of bias in animal studies was evaluated using the SYRCLE tool. Out of the 174 studies retrieved, 34 studies met the inclusion criteria (34 studies were analyzed in vitro and 20 studies were analyzed in vivo). The findings of the included studies revealed that DMOG stimulated stem cells' differentiation toward osteogenic, angiogenic, and chondrogenic lineages, leading to vascularized bone and cartilage regeneration. Addtionally, DMOG demonstrated therapeutic effects on bone loss caused by bone-related diseases. However, the culture environment in vitro is notably distinct from that in vivo, and the animal models used in vivo experiments differ significantly from humans. In summary, DMOG has the ability to enhance the osteogenic and angiogenic differentiation potential of stem cells, thereby improving bone regeneration in cases of bone defects. This highlights DMOG as a potential focus for research in the field of bone tissue regeneration engineering.

Platelet-rich fibrin in dentistry

OBJECTIVES

To review the progress of Platelet Rich Fibrin (PRF) as a biomaterial in dentistry and to highlight its promising application as a safe and biocompatible autologous platelet concentrate. Publications were searched in GeenMedical, X-mol, GoogleScholar, and PubMed from October 2024 with no language restrictions. The literature was searched for relevant databases and journals on the use of PRFs in dentistry up to October 2024, and the inclusion criteria included randomized controlled trials, clinical trials, case series, and systematic reviews.

CONCLUSION

PRF is a second-generation platelet concentrate that is sourced from oneself, has fewer adverse effects, and is simple and safe to prepare. These materials include growth factors and fibrin scaffolds, which are extensively utilized in regenerative medicine. By outlining PRF, we found that good results can be achieved when PRF is used to treat these conditions.

CLINICAL SIGNIFICANCE

The application of PRF in dentistry is widespread, particularly in periodontal soft and hard tissue regeneration, oral lichen planus, and pulpal regeneration. This article reviews the background, classification, and preparation methods of PRFs, along with their dental applications. We anticipate further research on various PRF derivatives in the future, which will significantly improve the utilization of PRF in oral applications and offer fresh insights for diagnosing and treating oral diseases.

Long noncoding RNA KCNMA1-AS1 promotes osteogenic differentiation of human bone marrow mesenchymal stem cells by activating the SMAD9 signaling pathway

The human bone marrow mesenchymal stem cells (hBMSCs) undergo intense osteogenic differentiation, a crucial bone formation mechanism. Evidence from prior studies suggested an association between long noncoding RNAs (lncRNAs) and the osteogenic differentiation of hBMSCs. However, precise roles and molecular mechanisms are still largely unknown. In this work, we report for the first time that lncRNA KCNMA1 antisense RNA 1 (KCNMA1-AS1) plays a vital role in regulating hBMSCs' osteogenic differentiation. Here, it was observed that the KCNMA1-AS1 expression levels were significantly upregulated during osteogenic differentiation. In addition, KCNMA1-AS1 overexpression enhanced in vitro osteogenic differentiation of hBMSCs and in vivo bone formation, whereas knockdown of KCNMA1-AS1 resulted in the opposite result. Additionally, the interaction between KCNMA1-AS1 and mothers against decapentaplegic homolog 9 (SMAD9) was confirmed by an RNA pull-down experiment, mass spectrometry, and RIP assay. This interaction regulated the activation of the SMAD9 signaling pathway. Moreover, rescue assays demonstrated that the inhibitor of the SMAD9 signaling pathway reversed the stimulative effects on osteogenic differentiation of hBMSCs by KCNMA1-AS1 overexpression. Altogether, our results stipulate that KCNMA1-AS1 promotes osteogenic differentiation of hBMSCs via activating the SMAD9 signaling pathway and can serve as a biomarker and therapeutic target in treating bone defects.