miR-196a-5p Promoted the Osteogenic Differentiation and Calvarial Bone Defect Repair of Wharton’s Jelly Umbilical Cord Stem Cells

Background: To investigate the effect of miR‐196a-5p on the osteogenic differentiation and defected bone repair of Wharton’s jelly umbilical cord stem cells (WJCMSCs). Methods: miR‐196a-5p mimic or inhibitor was applied to overexpress or silence miR‐196a-5p expression in WJCMSCs. The alkaline phosphatase (ALP) activity, mineralization ability, and osteogenic markers expression were used to test WJCMSCs osteogenic potential in vitro. Calvarial bone defect model of rat was used to evaluate WJCMSCs bone regeneration ability in vivo. mRNA microarray was used to reveal the underling mechanisms that miR‐196a-5p regulated bone repair.Results: miR-196a-5p inhibition reduced the ALP activity, mineralization ability, and level of osteogenic markers OCN, DSPP, DMP1 and BSP, while miR-196a-5p overexpression enhanced the ALP activity, mineralization ability, and level of OCN, DSPP, DMP1 and BSP of WJCMSCs in vitro. Next, the micro-CT and histopathology results showed miR-196a-5p-overexpressed-WJCMSCs obviously promoted the new bone tissue regeneration and calvarial bone defect repair after MSCs transplanted for 12 weeks. Further, mRNA microarray of miR-196a-5p-overexpressed-WJCMSCs revealed totally 959 significantly differentially expressed genes (DEGs), among which 34 upregulated and 925 downregulated. Also, 241 miR-196a-5p targeted genes were predicted by using miRNA targeted websites and only 19 predicted genes were consistent with microarray results. On this basis, one significantly downregulated gene SERPINB2 was selected and revealed that SERPINB2 deletion obviously enhanced the ALP activity and mineralization ability of WJCMSCs in vitro.Conclusions: miR-196a-5p promoted the osteogenic differentiation potential and calvarial bone defect repair ability of WJCMSCs. And SERPINB2 acted as one key downstream gene to participate in the miR-196a-5p promoted MSCs osteogenic differentiation.

The immunogenic reaction and bone defect repair function of ε-poly-L-lysine (EPL)-coated nanoscale PCL/HA scaffold in rabbit calvarial bone defect

Tissue engineering is a promising strategy for bone tissue defect reconstruction. Immunogenic reaction, which was induced by scaffolds degradation or contaminating microorganism, influence cellular activity, compromise the efficiency of tissue engineering, or eventually lead to the failure of regeneration. Inhibiting excessive immune response through modulating scaffold is critical important to promote tissue regeneration. Our previous study showed that ε-poly-L-lysine (EPL)-coated nanoscale polycaprolactone/hydroxyapatite (EPL/PCL/HA) composite scaffold has enhanced antibacterial and osteogenic properties in vitro. However, the bone defect repair function and immunogenic reaction of EPL/PCL/HA scaffolds in vivo remains unclear. In the present study, three nanoscale scaffolds (EPL/PCL/HA, PCL and PCL/HA) were transplanted into rabbit paraspinal muscle pouches, and T helper type 1 (Th1), T helper type 2 (Th2), T helper type 17 (Th17), and macrophage infiltration were analyzed after 1 week and 2 weeks to detect their immunogenic reaction. Then, the different scaffolds were transplanted into rabbit calvarial bone defect to compare the bone defect repair capacities. The results showed that EPL/PCL/HA composite scaffolds decreased pro-inflammatory Th1, Th17, and type I macrophage infiltration from 1 to 2 weeks, and increased anti-inflammatory Th2 infiltration into the regenerated area at 2 weeks in vivo, when compared to PCL and PCL/HA. In addition, EPL/PCL/HA showed an enhanced bone repair capacity compared to PCL and PCL/HA when transplanted into rabbit calvarial bone defects at both 4 and 8 weeks. Hence, our results suggest that EPL could regulate the immunogenic reaction and promote bone defect repair function of PCL/HA, which is a promising agent for tissue engineering scaffold modulation.

Bone regeneration in ceramic scaffolds with variable concentrations of PDRN and rhBMP-2

This study evaluated the bone regeneration capacity and mechanical properties of block-type hydroxyapatite (HA)/tricalcium phosphate (TCP) scaffolds in response to different concentrations of polydeoxyribonucleotide (PDRN) and recombinant human bone morphogenic protein 2 (rhBMP-2). Thirty-two male white rabbits were used as a model of calvarial bone defect and classified into eight groups according to type and concentration of growth factor administered, viz., control group (only HA/TCP scaffold), scaffold + PDRN (0.1, 1, 5, and 10 mg/mL each) and scaffold + rhBMP-2 (0.01, 0.05, and 0.1 mg/mL each). The specimens were evaluated using histomorphometric and radiological analyses. Histomorphometric analyses indicated that the administration of PDRN did not increase bone formation. However, significant increases in bone formation were observed with the administration of rhBMP-2 at 0.05 and 0.10 mg/mL on week 8 compared to the control (p < 0.05). Radiological analyses revealed a significant increase in bone formation at week 8 with the administration of PDRN at 5 mg/mL and 10 mg/mL, and rhBMP-2 at 0.05 or 0.10 mg/mL compared to the control (p < 0.05). Our findings show that block-type HA/TCP scaffolds possess sufficient mechanical strength and bone regeneration capacity when used with optimal concentrations of growth factors.

In Vitro Prevascularization of Self-Assembled Human Bone-Like Tissues and Preclinical Assessment Using a Rat Calvarial Bone Defect Model

In vitro prevascularization has the potential to address the challenge of maintaining cell viability at the core of engineered constructs, such as bone substitutes, and to improve the survival of tissue grafts by allowing quicker anastomosis to the host microvasculature. The self-assembly approach of tissue engineering allows the production of biomimetic bone-like tissue constructs including extracellular matrix and living human adipose-derived stromal/stem cells (hASCs) induced towards osteogenic differentiation. We hypothesized that the addition of endothelial cells could improve osteogenesis and biomineralization during the production of self-assembled human bone-like tissues using hASCs. Additionally, we postulated that these prevascularized constructs would consequently improve graft survival and bone repair of rat calvarial bone defects. This study shows that a dense capillary network spontaneously formed in vitro during tissue biofabrication after two weeks of maturation. Despite reductions in osteocalcin levels and hydroxyapatite formation in vitro in prevascularized bone-like tissues (35 days of culture), in vivo imaging of prevascularized constructs showed an improvement in cell survival without impeding bone healing after 12 weeks of implantation in a calvarial bone defect model (immunocompromised male rats), compared to their stromal counterparts. Globally, these findings establish our ability to engineer prevascularized bone-like tissues with improved functional properties.

ALLOGRAFT BONE APPLICATION IN THE RAT CALVARIAL BONE DEFECT MODEL: A HISTOPATHOLOGICAL STUDY

Trauma, neoplasms, infections, and congenital anomalies may be the reason for the calvarial bone defects. For eliminating bone defects in the cranial region to stimulate bone regeneration different graft types have been tried. In our study, we aimed to investigate the effects of allograft application in the rat calvarial bone defect model. For this purpose, 14 Wistar male rats were determined; defect (n=7) and defect + graft (n=7) groups. . The frontal bone was opened and a circular full thickness bone defect (5 mm) was created in the midline. Allograft material was placed in the defect area. All animals were sacriced after 28 days and the calvarial bones were followed up for routine histologic preparations. Sections were stained with H-E and scoring for histopathological parameters (inammation, brosis, osteoclast number, osteoblast number, osteocyte number, matrix formation, new bone trabecular diameter). In our study, inammation, brosis and osteoclast numbers decreased in the defect + graft group compared to the defect group, and osteocyte, osteoblast, matrix formation and bone trabecular diameter has increased signicantly. Histopathological evaluation revealed scar tissue, increased mononuclear cell inltration, and necrosis in the defect group. In the defect + graft group, an increase in collagen ber, a decrease in inammatory cells, an increase in osteoblast cells and bone matrix were observed. As a result, allograft application has been found to support new bone formation in the calvarial defect model by creating an osteoinductive and osteoconductive effect.

Effect of doxycycline-bioglass treatment on calvarial bone defect in rats: A histological study

Purpose: To evaluate the osteogenic properties of a bioglass-doxycycline complex for bone regeneration applications in calvarial bone defects in rats.Methods: Three critical-size bone defects were created in each of eight experimental rats using a trephine bur. The experimentally created defects were then filled with bioglass-doxycycline (BG-D group), bioglass alone (BG group), or left unfilled (control group). Four randomly selected rats weresacrificed after 4 weeks while the other four rats were sacrificed after 8 weeks. The amount of newly regenerated bone and the osteoblast and osteoclast counts were calculated using histological analysis.Results: Increase in the amount of regenerated bone was significant in the bioglass-doxycycline group at both 4 and 8 weeks (p < 0.05). Differences between the three groups in the mean number of osteoblasts were also significant at both 4 and 8 weeks (p < 0.05). Comparison of the three groupsrevealed significant increase in osteogenesis rate and considerable enhancement of the number of osteoblasts in both bioglass and bioglass-doxycycline groups (p < 0.05).Conclusion: The complex of doxycycline and bioglass increased the rate of osteogenesis and number of osteoblasts in rats but decreased the number of osteoclasts. Therefore, bioglass-doxycycline can be considered as a bone graft in bone regeneration for medical applications. Keywords: Bone, Regeneration, Osteoblasts, Osteoclasts, Osteogenesis, Bioglass, Doxycycline