Objective To review the research progress of in-situ three dimensional (3D) bio-printing technology in the repair of bone and cartilage injuries. Methods Literature on the application of in-situ 3D bio-printing technology to repair bone and cartilage injuries at home and abroad in recent years was reviewed, analyzed, and summarized. Results As a new tissue engineering technology, in-situ 3D bio-printing technology is mainly applied to repair bone, cartilage, and skin tissue injuries. By combining biomaterials, bioactive substances, and cells, tissue is printed directly at the site of injury or defect. At present, the research on the technology mainly focuses on printing mode, bio-ink, and printing technology; the application research in the field of bone and cartilage mainly focuses on pre-vascularization, adjusting the composition of bio-ink, improving scaffold structure, printing technology, loading drugs, cells, and bioactive factors, so as to promote tissue injury repair. Conclusion Multiple animal experiments have confirmed that in-situ 3D bio-printing technology can construct bone and cartilage tissue grafts in a real-time, rapid, and minimally invasive manner. In the future, it is necessary to continue to develop bio-inks suitable for specific tissue grafts, as well as combine with robotics, fusion imaging, and computer-aided medicine to improve printing efficiency.
Objective To investigate the expression levels of osteoprotegerin (OPG) and receptor activator of NF-κB l igand (RANKL) mRNAs in bone tissues of the femoral head of the patients suffering glucocorticoid-induced osteonecrosisof the femoral head (ONFH), and to discuss the relationship between OPG/RANKL and ONFH. Methods Between March2007 and March 2008, bone tissues of the femoral head were collected as the experimental material from 35 patients suffering ONFH (experimental group) and from 21 patients suffering fracture of femoral neck (control group). The ratio of men to women in both groups was 4 ∶ 3, whose age was 41-70 years old (55.34 on average in the experimental group and 55.33 on average in the control group). The experimental group received over 3 weeks’ glucocorticoid treatment or more than 1 week’ s high-dose glucocorticoid treatment in recent 2 years, while the control group never received more than 1 week’s hormone treatment. In the two groups, the microstructure of bone tissues of the femoral head was detected by HE staining and the bone tissue total RNA was extracted, and then the expression levels of OPG mRNA and RANKL mRNA were examined by realtime quantitative PCR (RTQ-PCR) for each sample. Results HE staining: bone trabeculae and bone units were replaced by interrupted bone fragments, which were surrounded by many inflammatory granulation tissues and few osteocytes were seen in bone lacunae in the experimental group. In the control group, bone trabeculae and bone units were made by complete lamellar bones which surrounded blood vessels and osteocytes were seen in lacunae. RTQ-PCR testing: in the experimental group, OPG mRNA and RANKL mRNA were 1.35 ± 0.42 and 4.36 ± 1.35, respectively, while in the control group they were 1.78 ± 0.63 and 3.49 ± 1.02, respectively. The expression level of OPG mRNA in the experimental group was significantly lower than that in the control group, and the expression level of RANKL mRNA of the former was significantly higher than the latter. The OPG mRNA/ RANKL mRNA ratio in the xperiment group (0.34 ± 0.16) was significantly lower than that in the control group (0.54 ± 0.20), and there was significant difference (P lt; 0.05). Conclusion The glucocorticoid-induced ONFH may be related to the expression levels of OPG mRNA/RANKL mRNA in bone tissues.
Objective To investigate the effect of glucocorticoid on the expression levels of osteoprotegerin (OPG)/receptor activator of nuclear factor kappa B ligand (RANKL)-matrix metalloproteinases (MMP)/tissue inhibitor of matrix metalloproteinase (TIMP) system in bone tissues of femoral head of rats, and to discuss its interrelated action mechanism in glucocorticoid-induced avascular necrosis of femoral head (ANFH). Methods Forty adult Sprague Dawley rats, weighing 250-300 g, half males and half females, were randomly divided into 4 groups: high dose glucocorticoid group (HD, n=10), medium dose glucocorticoid group (MD, n=10), low dose glucocorticoid group (LD, n=10), and control group (n=10). The rats in HD group, MD group, and LD group were intramuscularly injected with 25.0, 12.5, and 7.0 mg/kg of prednisolone respectively, and the rats in the control group were injected with physiological saline. After 4 weeks intervention, the osteonecrosis of left femoral heads was observed by HE staining, total RNA was extracted from the right femoral head bone tissue and the mRNA expression levels of OPG, RANKL, MMP-2, MMP-9, TIMP-1, and TIMP-2 were detected by RT-PCR. Results After injection of prednisolone, 4 rats of HD group and 1 rat of MD group died of systemic failure caused by the decreased food and weight culminating in cachexia. HE staining showed that the integrity of bone trabecula and osteon was destroyed at different levels, discontinuous bone chips formed, and osteocytes were replaced by granulation tissue in some lacunae in HD, MD, and LD groups; the integrated osteon was observed, the lamellar structure formed concentric circles around the blood vessel and osteocytes were seen in the lacunae in the control group. The necrosis rates of femoral head were 83.3% (5/6), 66.7% (6/9), 30.0% (3/10), and 0 (0/10) in HD, MD, LD, and control groups. The results of RT-PCR showed: the mRNA expression levels of the OPG, TIMP-1, TIMP-2 in HD, MD, and LD groups were lower than those in the control group, showing significant differences (P lt; 0.05) and there was negative correlation with the hormone dosage. The difference in OPG expression was significant between the hormone groups (P lt; 0.05); the differences in the TIMP-1 and TIMP-2 expressions were not significant between the LD group and MD group (P gt; 0.05), but there were significant differences when compared with HD group (P lt; 0.05). The RANKL, MMP-2, and MMP-9 mRNA expression levels in HD, MD, and LD groups were higher than those in the control group and there was a positive correlation with the hormone dosage, showing significant differences when compared MD and HD groups with control group (P lt; 0.05); there was no significant difference in RANKL expression between HD group and MD group (P gt; 0.05), but there was significant difference when compared HD and MD groups with LD group (P gt; 0.05); no significant difference was observed in the MMP-2 and MMP-9 expression between MD group and LD group (P gt; 0.05), but the differences were significant when compared with HD group (P lt; 0.05). Conclusion Glucocorticoid-induced ANFH may be related to the expression levels of OPG/RANKL-MMP/TIMP mRNA regulated by glucocorticoid.
Objective To study the improved index finger dorsal island flap for primary repair of thumb tip injury. Methods Between January 2009 and February 2010, 23 patients with thumb tip injury were treated. There were 17 males and 6 females, aged 21-47 years (mean, 27.5 years). The causes of injury were mechanical injury in 18 cases and heavy crushing injury in 5 cases. The time from injury to operation was 2.5-5.0 hours (mean, 3.5 hours). The defect locations included ulnar palmar defect in 5 cases, dorsal foot defect in 6 cases, radial palmar defect in 8 cases, and radial dorsal defect in 4 cases. All patients complicated by exposure of the thumb distal phalanx. The wound area varied from 2.1 cm × 1.8 cm to 2.8 cm × 2.5 cm. According to distal soft tissue defect of thumb, a modified index finger dorsal island flap was designed, key point of which was moved forward, and defects were repaired with the flaps. The size of flap was 2.3 cm × 2.0 cm to 3.0 cm × 2.7 cm. The donor sites were repaired with skin graft. Results All the flaps and grafts survived after operation and the wounds healed by first intention. All patients were followed up 6-12 months with an average of 6.4 months. The appearance and texture of the flaps were excellent. At last follow-up, the sensation of the flaps recovered to S3+ in 18 cases, to S3 in 2 cases, and to S2 in 3 cases. The two-point discrimination was 3-4 mm. Thumb opposition function was normal without contracture at the first web space. The skin graft at the donor site survived completely, and the metacarpophalangeal joint at donor site had the flexion and extension function. Conclusion Using a modified index finger dorsal island flap for primary repair thumb tip injury is a simple operation, which has good blood supply and high survival rate. When the pedicle flap rotation point is moved forward 10 mm or more, it can meet the needs of repairing thumb tip defect.
Objective To investigate the expression levels of osteoprotegerin (OPG) and receptor activator of nuclear factor kappa B l igand (RANKL) mRNAs in BMSCs in patients suffering glucocorticoid-induced necrosis of the femoral head (GNFH), and to discuss the relationshi p between OPG/RANKL system and GNFH. Methods The bone tissue and BMSCs of femoral head were collected from 35 patients suffering GNFH (experimental group) and from 21 patients suffering fracture of femoral neck (control group). The ratio of men to women was 4 ∶ 3 in two groups, aged 41 to 70 years (mean 55.34years in the experimental group and mean 55.33 years in the control group). The patients of experimental group received over 3 weeks’ glucocorticoid treatment or more than 1 week’s high-dose glucocorticoid therapy in recent 2 years, but patients of the control group did not receive more than 1 week’s hormone therapy. In 2 groups, the microstructure of bone tissue of femoral head was detected by HE staining. The BMSCs were isolated and cultured by adherent-wall method; the expression levels of OPG and RANKL mRNAs were examined by real-time quantitative polymerase chain reaction and the ratio of OPG mRNA to RANKL mRNA was caculated. Results Bone trabeculae and bone units were replaced by interrupted bone fragments, which were surrounded by inflammation and granulation tissue and few osteocytes were seen in bone lacunae in the experimental group. In control group, bone trabeculae and bone units were made by complete lamellar bone which surrounded blood vessels and osteocytes were seen in lacunae. The expression levels of OPG mRNA in the experimental group (0.37 ± 0.12) was significantly lower than that in the control group (0.47 ± 0.13), and the levels of RANKL mRNA in the experimental group (1.12 ± 0.39) was significantly higher than that in the control group (0.84 ± 0.24), showing statistically significant difference (P lt; 0.05). The ratio of OPG mRNA to RANKL mRNA in the experimental group (0.37 ± 0.17) was significantly lower than that in the control group (0.61 ± 0.26, P lt; 0.05). Conclusion The GNFH may be related to the expression levels of OPG mRNA and RANKL mRNA in BMSCs.