Biomedical subjects

Zhou Xiang

Publications and source records attributed to Zhou Xiang.

10 recordsLinked to original sources

PubMed2006

Early bone apposition in vivo on plasma-sprayed and electrochemically deposited hydroxyapatite coatings on titanium alloy.

Three different implants, bare Ti-6Al-4V alloy, Ti-6Al-4V alloy coated with plasma-sprayed hydroxyapatite (PSHA), and Ti-6Al-4V alloy coated with electrochemically deposited hydroxyapatite (EDHA), were implanted into canine trabecular bone for 6 h, 7, and 14 days, respectively. Environmental scanning electron microscopy study showed that PSHA coatings had higher bone apposition ratios than those exhibited by bare Ti-6Al-4V and EDHA coatings after 7 days; however, at 14 days after implantation, EDHA and PSHA coatings exhibited similar bone apposition ratios, much higher than that for bare Ti-6Al-4V. The ultrastructure of the bone/implant interface observed by transmission electron microscope showed that the earliest mineralization (6 h-7 days) was in the form of nano-ribbon cluster mineral deposits with a Ca/P atomic ratio lower than that of hydroxyapatite. Later-stage mineralization (7-14 days) resulted in bone-like tissue with the characteristic templating of self-assembled collagen fibrils by HA platelets. Though adhesion of EDHA coatings to Ti-6Al-4V substrate proved problematical and clearly needs to be addressed through appropriate manipulation of electrodepositon parameters, the finely textured microstructure of EDHA coatings appears to provide significant advantage for the integration of mineralized bone tissue into the coatings.

Alloys↗

PubMed2006

Collagen-GAG scaffolds grafted onto myocardial infarcts in a rat model: a delivery vehicle for mesenchymal stem cells.

Various cell delivery methods have been investigated for cell transplantation treatment of cardiac infarcts. In this study, we investigated a type I collagen-glycosaminoglycan (GAG) scaffold for the implantation of adult bone marrow-derived mesenchymal stem cells (MSCs) into the infarcted region in the rat heart. The objective was to evaluate the tissue response to collagen-GAG scaffolds prepared using 2 cross-linking methods. The left coronary artery of female Wistar rats was occluded for 60 min, followed by reperfusion. One week later, the infarcted region was implanted with (1) collagen-GAG scaffolds cross-linked by dehydrothermal treatment alone (DHT; n = 10); (2) collagen-GAG scaffolds cross-linked by DHT followed by carbodiimide treatment (EDAC; n = 8); or (3) DHT cross-linked collagen-GAG scaffolds seeded with bromodeoxyuridine (BrdU)-labeled allogeneic MSCs (cell-scaffold; n = 9). Shamoperated rats served as controls (n = 4). Specimens were harvested 3 weeks after the implantation surgery. The tissue response was evaluated histomorphometrically and by immunohistochemistry to track the BrdU-labeled MSCs. Most of the DHT cross-linked collagen-GAG scaffolds degraded, whereas the scaffolds in the EDAC group appeared to be largely intact. There were no signs of acute inflammation in any of the groups. A substantial amount of neovascularization was seen in the infarcted region in the implant groups and in the scaffolds themselves. BrdU-positive cells appeared both in the degraded scaffold and the infarct region. DHT cross-linked collagen-GAG scaffolds warrant continued investigation as delivery vehicles for implantation of cells into infarcted cardiac tissue.

Absorbable Implants↗

PubMed2006

Preliminary study of mesenchymal stem cells-seeded type I collagen-glycosaminoglycan matrices for cartilage repair.

OBJECTIVE: To investigate the possibility of repairing articular cartilage defects with the mesenchymal stem cells (MSCs)- seeded type I collagen-glycosaminoglycan(CG) matrices after being cultured with the chondrogenic differentiation medium. METHODS: The adherent population of MSCs from bone marrow of 10 adult dogs were expanded in number to the 3rd passage. MSCs were seeded into the dehydrothermal treatment (DHT) cross-linked CG matrices; 2 x 10(6) cells per 9-mm diameter samples were taken. Chondrogenic differentiation was achieved by the induction media for 3 weeks. Cell contractility was evaluated by the measurement of the cell-mediated contraction of the CG matrices with time in culture. The in vitro formation of the cartilage was assessed by an assay employing immunohistochemical identification of type II collagen and by immunohistochemistry to demonstrate smooth muscle actin (SMA). The cells seedling CGs were implanted into cartilage defects of canine knee joints. Twelve weeks after surgery, the dogs were sacrificed and results were observed. RESULTS: There was significant contraction of the MSCs-seeded DHT cross-linked CG scaffolds cultured in the cartilage induction medium. After 21 days, the MSC-seeded DHT cross-linked matrices were contracted to 64.4% +/- 0.3%; histologically, the pores were found to be compressed and the contraction coupled with the newly synthesized matrix, transforming the MSCs-seeded CG matrix into a solid tissue in most areas. The type II collagen staining was positive. The SMA staining was positive when these MSCs were seeded and the contracted CGs were implanted into the cartilage defects of the canine knee joints to repair the cartilage defects. The function of the knee joints recovered and the solid cartilaginous tissue filled the cartilage defects. Conclusion The results demonstrates that MSCs grown in the CG matrices can produce a solid cartilaginous tissue containing type II collagen after being cultured with the chondrogenic differentiation medium and implanted into cartilage defects. We hypothesize that the following steps can be performed in the chondrogenic process: (1)MSCs express SMA, resulting in matrix contraction, thus achieving a required cell density (allowing the cells to operate in a necessary society); (2)Cells interact to form a type II collagen-containing extracellular matrix (and cartilaginous tissue); (3)Other factors, such as an applied mechanical stress, may be required to form a mature cartilage with the normal architecture.

Animals↗

PubMed2005

Systematic off-pump coronary artery bypass.

PURPOSE: We assessed the feasibility of systematic off-pump coronary artery bypass (OPCAB) and identified risk factors for on-pump conversion. METHODS: Between July 1, 2002 and December 31, 2003, OPCAB was attempted for all patients who required isolated coronary artery bypass in our institution. The perioperative results of patients were prospectively entered into a structured database, the results were analyzed to identify the risks of requirement of cardiopulmonary bypass. RESULTS: OPCAB was performed in all but 4 patients, giving an OPCAB success rate of 98.3% (229/233). The reason for cardiopulmonary bypass was hemodynamic instability occurring during reoperative surgery in 3, and cardiogenic shock in 1. The isolated risk factor for on-pump conversion was reoperation (relative risk 11.6). Mean number of distal anastomoses performed under OPCAB was 3.7+/-1.2, and the complete revascularization rate was 92.1% (211/229). There was one hospital death (0.4%). During a mean follow-up period of 1.0+/-0.4 years, two patients developed angina, which were treated with catheter intervention; otherwise, there was no death, or other cardiac events observed. CONCLUSION: Systematic OPCAB was feasible except in patients undergoing reoperative surgery or patients with on-going deep cardiogenic shock. Systematic OPCAB provided successful complete revascularization and its short term results were acceptable.

Aged↗

PubMed2005

[The application of basic fibroblast growth factor in tendon tissue engineering].

OBJECTIVE: To review the recent researches of basic fibroblast growth factor (bFGF) in tendon tissue engineering. METHODS: Recent original related literature was extensively reviewed and analyzed. RESULTS: bFGF played an important role in establishing standard tendon tissue engineering cell lines, inducing the compound and analysis of extracellular matrix, enhancing interactions between cells and extracellular matrix and accelerating tissue engineering materials' neovascularization. CONCLUSION: The progresses in increasing endogenetic bFGF expression, controlling the release of exogenous bFGF and improving the bio-utilization of bFGF has laid foundation for wider use of bFGF in tendon tissue engineering.

Animals↗

PubMed2004

[Effect of autologous bone marrow mesenchymal stem cells and extrogenous sodium hyaluronate on repairing knee joint defect in rabbits].

OBJECTIVE: To explore the relationship of the limited resource of the autologous bone marrow mesenchymal stem cells (MSCs) in articular cavity to the treatment results of full-thickness articular cartilage defect, and to investigate whether the extrogenous sodium hyaluronate (SH) promotes the migration of MSCs cultured in vitro to the articular defect in vivo. METHODS: Sixty-six Japan rabbits were made the model of the full-thickness articular cartilage defect (5 mm width and 4 mm depth). The autologous MSCs were extracted from the rabbit femur, cultured in vitro, labeled by Brdu, and injected into the injured articular cavity with or without SH. The experiment was divided into 4 groups; group A (MSCs and SH, n=15); group B (MSCs, n=15); group C (SH, n=18); and group D (non-treatment, n=18). The morphologic observation was made by HE staining, Mallory staining and immunohistochemical staining after 5 weeks, 8 weeks and 12 weeks of operation. RESULTS: There were significant differences in the thickness of repairing tissue between group A and group B (P<0.01); but there were no significant differences between group A and group C, and between group B and group D (P>0.05). The histological observation showed that the main repairing tissue was fibrocartilage in group A and fiber tissue in group B. CONCLUSION: MSCs cultured in vitro and injected into the articular cavity can not improve the treatment results of the articular cartilage defect. Extrogenous SH has effect on repairing cartilage defect. The extrogenous SH has no effect on the chemotaxis of the MSCs, and on the collection of MSCs into the joint defect.

Animals↗

PubMed2002

A glimpse of tissue engineering in China.

Tissue engineering activities in China have expanded and advanced to the extent that it is not possible to acknowledge all of the work in one review. Substantial progress has been made in the development of novel biomaterial scaffolds and in the genetic manipulation of cells in vitro. Moreover, certain aspects of tissue engineering strategies have begun to undergo clinical trial. A glimpse of tissue engineering in China was afforded at the First International Conference on Biomaterials (China) held in Beijing, July 24-26, 2001. Several papers presented at the meeting, which was conducted in English only, reflected many of the tissue engineering activities in the country. A brief summary of some of the papers may begin to suggest possibilities for collaboration between tissue engineers inside and outside of China, as well as to facilitate dissemination of important findings.

China↗

PubMed2002

[Locking compression plate fixation for periprosthetic femoral fracture].

OBJECTIVE: To introduce a method for fixation in periprosthetic fracture with locking compression plate (LCP). METHODS: During the surgery, a long 12-hole LCP was placed to the lateral side of the femur. Six holes of the plate were placed proximal to the main fracture line to make sure that there could be enough cortex units for rigid fixation of proximal fragments. Locking screws used except for the most proximal hole where a 4.5 mm screw was used instead. RESULTS: The patient was pain free at the fracture site one week after the surgery, and was able to walk with a cane 3 months after the surgery. Bone union was evident radiographically 3 months after the surgery. There was no loose signs around the stem. Six months after the surgery, the patient recovered full function without pain. CONCLUSION: In our experience from this case, LCP in treating periprosthetic fracture was easy and less time consuming, more over, extensive periosteal stripping could be avoided. LCP is a good choice in treating some periprosthetic fractures.

Aged↗

PubMed2002

[Potential seeding cells for cartilage tissue engineering--bone marrow stromal stem cells].

OBJECTIVE: To review the recent research progress of bone-marrow stromal stem cells (BMSCs) in the conditions of culture in vitro, chondrogenic differentiation, and the application in cartilage tissue engineering. METHODS: Recent original articles related to such aspects of BMSCs were reviewed extensively. RESULTS: BMSCs are easy to be isolated and cultivated. In the process of chondrogenesis of BMSCs, the special factors and interaction between cells are investigated extensively. BMSCs have been identified to form cartilage in vivo. One theory is the committed chondrocyte from BMSCs is only a transient stage. CONCLUSION: BMSCs are the alternative seeding cells for cartilage tissue engineering. The conditions promoting mature chondrocyte should be further investigated.

Bone Marrow Cells↗

PubMedDate not supplied

Routine reoperative off-pump coronary artery bypass grafting via midline sternotomy: is it feasible?

Multivessel off-pump coronary artery bypass (OPCAB) has been conducted safely; however, the clinical outcomes of reoperative OPCAB have not been reported clearly. Currently OPCAB is being performed systematically in this institution including reoperative surgeries. Between September 1, 1999, and December 31, 2003, reoperative OPCAB via midline sternotomy was planned for nonemergent patients with normal left ventricular function without valvular disease. The perioperative results of patients who underwent reoperative OPCAB were analyzed. Thirty-five patients were scheduled for OPCAB. Of these, OPCAB was performed in 27 patients, giving OPCAB success rate of 77.1%. Failure of OPCAB was due to graft injury in 2, ischemic EKG change in 1, and dense adhesion and difficulty of dissection in 5 patients. The mean number of grafts with completed OPCAB was 3.0 +/- 1.5. There were no hospital deaths, strokes, or respiratory or renal failures. One patient (3.7%) developed perioperative myocardial infarction. Postoperative angiography was obtained in 12 patients (26 distal anastomoses), and all anastomoses were perfect except for 1 distal anastomosis stenosis, giving an overall stenosis-free patency rate of 95.1%. During a follow-up period (mean 2.5 +/- 0.6 years), all patients survived without cardiac event, except 1 patient who underwent catheter intervention. Cardiopulmonary bypass may be required during cardiac dissection to decompress the heart and to facilitate dissection. However, once lysis of the adhesion is completed, reoperative OPCAB can be performed without increasing surgical risks. Midterm results were satisfactory.

Aged↗