ABSTRACT
Objective@#To investigate the osteogenic properties of a methacrylated gelatin (GelMA) / bone marrow mesenchymal stem cells (BMSCs) composite hydrogel applied to the skull defect area of rats and to provide an experimental basis for the development of bone regeneration biomaterials.@*Methods@#This study was approved by the Animal Ethics Committee of Nanjing University. A novel photocurable composite biohydrogel was developed by constructing photoinitiators [lthium phenyl (2,4,6-trimethylbenzoyl) phosphinate, LAP], GelMA, and BMSCs. The surface morphology and elemental composition of the gel were examined using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). The compressive strength of the gel was evaluated using an electronic universal testing machine. After in vitro culture for 1, 2, and 5 days, the proliferation of the BMSCs in the hydrogels was assessed using a CCK-8 assay, and their survival and morphology were examined through confocal microscopy. A 5 mm critical bone deficiency model was generated in a rat skull. The group receiving composite hydrogel treatment was referred to as the GelMA/BMSCs group, whereas the untreated group served as the control group. At the 4th and 8th weeks, micro-CT scans were taken to measure the bone defect area and new bone index, while at the 8th week, skull samples from the defect area were subjected to H&E staining, van Gieson staining, and Goldner staining to evaluate the quality of bone regeneration and new bone formation.@*Results@#SEM observed that the solidified GelMA showed a 3D spongy gel network with uniform morphology, the porosity of GelMA was 73.41% and the pore size of GelMA was (28.75 ± 7.13) μm. EDX results showed that C and O were evenly distributed in the network macroporous structure of hydrogel. The hydrogel compression strength was 152 kPa. On the 5th day of GelMA/BMSCs culture, the cellular morphology transitioned from oval to spindle shaped under microscopic observation, accompanied by a significant increase in cell proliferation (159.4%, as determined by the CCK-8 assay). At 4 weeks after surgery, a 3D reconstructed micro-CT image revealed a minimal reduction in bone defect size within the control group and abundant new bone formation in the GelMA/BMSCs group. At 8 weeks after surgery, no significant changes were observed in the control group's bone defect area, with only limited evidence of new bone growth; however, substantial healing of skull defects was evident in the GelMA/BMSCs group. Quantitative analysis at both the 4- and 8-week examinations indicated significant improvements in the new bone volume (BV), new bone volume/total bone volume (BV/TV), bone surface (BS), and bone surface/total bone volume (BS/TV) in the GelMA/BMSCs group compared to those in the control group (P<0.05). Histological staining showed continuous and dense formation of bone tissue within the defects in the GelMA/BMSCs group and only sporadic formation of new bone, primarily consisting of fibrous connective tissue, at the defect edge in the control group.@*Conclusion@#Photocuring hydrogel-based stem cell therapy exhibits favorable biosafety profiles and has potential for clinical application by inducing new bone formation and promoting maturation within rat skull defects.
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Objective@#To evaluate the bone repair effect of 3D-printed magnesium (Mg)-loaded polycaprolactone (PCL) scaffolds in a rat skull defect model.@*Methods@#PCL scaffolds mixed with Mg microparticles were prepared by using 3D printing technology, as were pure PCL scaffolds. The surface morphologies of the two scaffolds were observed by scanning electron microscopy (SEM), and the surface elemental composition was analyzed via energy dispersive spectroscopy (EDS). The physical properties of the scaffolds were characterized through contact angle measurements and an electronic universal testing machine. This study has been reviewed and approved by the Ethics Committee. A critical size defect model was established in the skull of 15 Sprague-Dawley (SD) rats, which were divided into the PCL group, PCL-Mg group, and untreated group, with 5 rats in each group. Micro-CT scanning was performed to detect and analyze skull defect healing at 4 and 8 weeks after surgery, and samples from the skull defect area and major organs of the rats were obtained for histological staining at 8 weeks after surgery.@*Results@#The scaffolds had a pore size of (480 ± 25) μm, a fiber diameter of (300 ± 25) μm, and a porosity of approximately 66%. The PCL-Mg scaffolds contained 1.0 At% Mg, indicating successful incorporation of Mg microparticles. The contact angle of the PCL-Mg scaffolds was 68.97° ± 1.39°, indicating improved wettability compared to that of pure PCL scaffolds. Additionally, compared with that of pure PCL scaffolds, the compressive modulus of the PCL-Mg scaffolds was (57.37 ± 8.33) MPa, demonstrating enhanced strength. The PCL-Mg group exhibited the best bone formation behavior in the skull defect area compared with the control group and PCL group at 4 and 8 weeks after surgery. Moreover, quantitative parameters, such as bone volume (BV), bone volume/total volume (BV/TV), bone surface (BS), bone surface/total volume (BS/TV), trabecular thickness (Tb.Th), trabecular number (Tb.N) and bone mineral density (BMD), of skull defects were better than those in the other groups, indicating the best bone regeneration effect. H&E, Goldner, and VG staining revealed more mineralized new bone formation in the PCL-Mg group than in the other groups, and H&E staining of the major organs revealed good biosafety of the material.@*Conclusion@#PCL-Mg scaffolds can promote the repair of bone defects and have clinical potential as a new scaffold material for the repair of maxillofacial bone defects.
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Objective@# To analyze the current status, hotspots, and trends in the field of stem cell therapies for periodontal tissue engineering based on bibliometric analysis.@*Methods @# The literature on stem cell therapies for periodontal tissue engineering in animal experiments and clinical studies was searched in the Web of Science core database up to December 31, 2021. The bibliometric analysis of the relevant literature data was carried out by using the "Bibliometrix" package of R language.@*Results @#A total of 304 articles were included, and the number of publications and the citation frequency are increasing. The number of related studies from China ranks first in the world with 166 publications; the institution with the largest number of publications is the Fourth Military Medical University; the author with the largest number of publications is Jin Y; and Tissue Engineering Part A had the most related publications. The hotspots of stem cell therapies for periodontal tissue engineering are mainly focused on tissue engineering and periodontal ligament regeneration, while the frontiers are mainly focused on exosomes, gold nanoparticles, and angiogenesis. @*Conclusion@#Research on stem cell therapies for periodontal tissue engineering continues to expand, and the academic influence is gradually increasing. Future research directions should focus on periodontal ligament regeneration, exosomes, gold nanoparticles and angiogenesis.
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Objective @#This article explores the relationship between congenital tooth agenesis and related gene mutations, providing a reference for early diagnosis of the disease.@*Methods @# Clinical and radiographic examinations of a rare case of congenital tooth agenesis were conducted to evaluate the abnormal morphology and quantity of the teeth, as well as the overall health of the patient. Bidirectional sequencing of the PAX9 and MSX1 genes and whole-exome sequencing were conducted to identify potential genetic abnormalities. Sanger sequencing of the newly discovered mutation site was performed on the proband's son. Subsequently, the impacts of the mutations were evaluated through computational tools and a cell-based gene transfection assay. @*Results @#This is a rare case of tooth agenesis characterized by a congenitally missing first molar, a second molar with one single root and a supernumerary second premolar in the right mandibular dentition. The c.717 C>C/T in PAX9 is synonymous. The c.119C>G in MSX1 is a missense mutation predicted to be “benign” by Polyphen. Through whole-exome sequencing, we found a novel mutation, c.637-7 C>A in intron 3 of the WNT6 gene, which is predicted by MAXENT to influence the splicing of mRNA. Both the proband and his son carry this mutation. A cell-based gene transfection assay demonstrated that it did not alter the mRNA splicing of WNT6. @* Conclusion @#The interaction between single nucleotide polymorphisms may contribute to congenital tooth agenesis.