OBJECTIVE To study the biocompatibility on bioactive glass ceramics (BGC) and polylactic acid (PLA) combined with cultured bone marrow stromal cells (BMSCs) in bone tissue engineering. METHODS BMSCs were cultured combined with BGC and PLA in vitro, and the morphological characters, cell proliferation, protein content, and alkaline phosphatase activity were detected. RESULTS: BMSCs could be attached to and extended on both BGC and PLA, and normally grown, proliferated, had active function. BGC could promote cell proliferation. CONCLUSION The results show that both BGC and PLA have good biocompatibility with BMSCs, they can be used as biomaterials for cell transplantation in tissue engineering.
Objective To make a comparative study on the effects of whole bone marrow culture method and density gradient centrifugation method in isolating hBMSCs. Methods hBMSCs were obtained from healthy adult volunteers and isolated by whole bone marrow culture method and density gradient centrifugation method. Primary cell morphology was observed using inverted phase contrast microscope and the cells in the 2nd passage were stained with HE after being cultured for 7 days. And then, the generation time of the primary, 2nd and 3rd passage hBMSCs was comparedbetween two methods and the surface markers were detected by flow cytometer. In addition, the ALP expression inosteoinductive hBMSCs were evaluated by ALP activity kit at 3, 6 and 9 days and ALP staining was used for osteoinductivehBMSCs with Kaplow method at 9 days. Results Primary cells isolated with whole bone marrow culture method showedaggregation growth while cells isolated with density gradient centrifugation method showed diffusion growth. HE stainingshowed no significant difference in the morphology of the 2nd passage cells between these two methods. The generationtime of primary cells isolated by whole bone marrow culture method (15.36 ± 1.67) days was significantly shorter than that of cells isolated by density gradient centrifugation method [(18.57 ± 1.05) days] (P lt; 0.01), while the generation time of the 2nd and 3rd passage cells showed no statistically significant differences between these methods (P gt; 0.05). The concent of positive surface markers (CD29, CD44, CD71, CD105, CD166) and negative surface marker CD34 in the 2nd cells showed no significant difference between these two isolation methods (P gt; 0.05); however, negative markers CD14 and CD45 showed significant difference (P lt; 0.01). The ALP expression in osteoinductive cells showed no statistical significant (P gt; 0.05) at 3, 6 and 9 days; and the ALP staining positive cell ratio of whole bone marrow culture method was basically in accordance with that of density gradient centrifugation method at 9 days. Conclusion hBMSCs could be isolated by whole bone marrow culture method, and the cell isolation effects of whole bone marrow culture method are equivalent with density gradient centrifugation method.
Objective To explore the cytotoxicity, labeled time, marking rate, and effect on adhesion of quantum dot 655 (QD655) labeled rat bone marrow mesenchymal stem cells (BMSCs) in vitro, and to confirm its feasibil ity for stem cell label ing and tracer means for rat. Methods BMSCs were collected from the femur and tibia bone marrow cavity of a 2-week-old SD rat, cultured and identified. The 3rd passage of BMSCs were incubated with QD655 as the experimental groupaccording to the recommended concentration of the markers. The cells were not labeled by QD655 as control group. Thecell survival rate after QD655 label ing was detected by trypan-blue exclusion. The effect of QD655 on cell prol iferation was observed by MTT. The osteogenic differentiation potential was identified by Al izarin red staining, alkal ine phosphatase (ALP) staining, and real-time fluorogenic quantitative PCR. At immediately, 1, 2, 4, and 6 weeks, fluorescent microscopy was used to observe the labeled rate and scanning electron microscope was used to observe the cell adhesion to scaffold (bioglass/collagen composite). Results The cell survival rates were more than 90% in both experimental group and control group, showing no significant difference (P gt; 0.05). There was no significant difference in the cell prol iferation between 2 groups (P gt; 0.05). Al izarin red staining and ALP staining showed positive results. Real-time fluorogenic quantitative PCR result showed that the mRNA expression levels of osteopontin, osteocalcin, collagen type I, ALP, and BMP-2 in the experimental group was significantly higher than those in the control group. The labeled rates were 96.50% ± 1.59%, 93.30% ± 1.51%, 72.40% ± 2.90%, 40.10% ± 3.60%, and 10.00% ± 1.70% immediately, 1, 2, 4, and 6 weeks after label ing, respectively. The labeled rate in the control group was 0. Scanning electron microscope showed a good distribution of fusiform or polygonal cells in the pores of scaffold. Conclusion QD655 can be used as a label ing marker for BMSCs. Rat BMSCs labeled with QD655 is of high efficiency and safety.
Objective To explore the effects of calcitonin gene-related peptide (CGRP) on the migration of bone marrow mesenchymal stem cells (BMSCs) and vascular endothel ial growth factor (VEGF) expression in vitro. Methods TheBMSCs were isolated from Sprague Dawley rats using whole bone marrow adherence method. At 1, 2, and 3 weeks after culture, the expressions of CGRP receptor (CGRPR) was detected by Western blot. The BMSCs were treated with CGRP at concentration 1 × 10-8 mol/L (experimental group) and did not treated (control group), and the efficacy of BMSCs migration was analyzed by Transwell chamber assay after 72 hours; at 1, 3, 5, and 7 days, the mRNA expressions of vascular cell adhesion molecule 1 (VCAM-1) were detected by real-time fluorescent quantitative PCR; the protein expressions of VEGF were examined using immunohistochemistry and Western blot. Results CGRPR expressed stably in the cultured BMSCs and reached the peak at 2 weeks. CGRP had a significantly enhanced role in promoting cell migration. The number of cell migration was (3.20 ± 1.77) cells/HP in experimental group and (1.11 ± 0.49) cells/HP in control group, showing significant difference (t=4.230, P=0.001). In experimental group, the expressions of VCAM-1 mRNA increased with time and reached the peak at 7 days. There were significant differences in the expressions of VCAM-1 mRNA between control group and experimental group at 3, 5, and 7 days (P lt; 0.05). Immunocytochemistry results showed positive DAB staining for VEGF at 5 and 7 days in experimental group. Western blot results showed that the protein expressions of VEGF increased significantly at 5 and 7 days in experimental group when compared with control group (P lt; 0.05), which was signfiantly higher at 5 days than at 7 days in experimental group (P lt; 0.05). Conclusion CGRP can promote the migration of BMSCs and stimulate the protein expression of VEGF, which may plays an important role in regulating bone metabol ism by increasing angiogenesis.
Objective Rapid and effective vascularization of scaffolds used for bone tissue engineering is critical to bony repair. To study the cooperative and promotion effects of enhanced bioactive glass/collagen composite scaffold on vascularization for searching for a kind of el igible vascularized scaffold to repair bone defect. Methods The human umbil ical vein endothel ial cells (HUVECs) were collected from human umbil ical core, and identified through von Willebrandfactor (vWF) and CD34 immunofluorescence. The 1st passage of HUVECs were suspensed and seeded into the scaffold. The attachment and prol iferation of HUVECs on the scaffold were observed through scanning electron microscope (SEM). HUVECs were seeded on the scaffold as the experimental group, and on 96-well plate as the control group. The growth rate of HUVECs was detected through alarmarBlue at 1, 3, 5, 7, 9, and 11 days. Meanwhile, the mRNA expression levels of VEGF, fms-related tyrosine kinase 1 (Flt-1), and kinase insert domain receptor (Kdr) were detected through real-time fluorescence quantitative PCR. Twelve scaffolds were embedded subcutaneouly into 6 Sprague-Dawley rats. The enhanced scaffolds were used and the arteria and vein saphena bundle were embedded straightly through the central slot of scaffold in experimental group, and the common scaffolds were used in control group. Frozen section and HE staining of scaffolds were performed at 5 days and 10 days to observe the vascularization of embedded scaffold. Results HUVECs were identified through morphology, vWF and CD34 immunofluorescence. SEM results showed HUVECs could attach to the scaffold tightly and viably. HUVECs prol iferated actively on the scaffold in experimental group; the growth rate in experimental group was higher than that in control group at 3-11 days, showing significant differences within 5-11 days (P lt; 0.05). The real-time fluorescence quantitative PCR results showed thatthe mRNA expression levels of VEGF, Flt-1, and Kdr in experimental group were higher than those in control group at 3 days, showing significant differences (P lt; 0.05). Frozen section and HE staining of the scaffolds in experimental group showed that the embedded vessel bundle were still patency at 5 days and 10 days, that many new vessels were observed around the embedded vessel bundle and increased with time, host vessels infiltrated in the surrounding area of scaffold and fewer neo-vessels at the distant area. But there was only some fibrous tissue appeared in control group, and at 10 days, the common scaffold degradated, so few normal tissue appeared at the embedded area. Conclusion Enhanced bioactive glass/collagen composite scaffold can promote vascularization in vitro and in vivo, and may be used in bone tissue engineering.