Metabolic Glycoengineering: A Promising Strategy to Remodel Microenvironments for Regenerative Therapy.

Cell-based regenerative therapy utilizes the differentiation potential of stem cells to rejuvenate tissues. But the dynamic fate of stem cells is calling for precise control to optimize their therapeutic efficiency. Stem cell fate is regulated by specific conditions called "microenvironments." Among the various factors in the microenvironment, the cell-surface glycan acts as a mediator of cell-matrix and cell-cell interactions and manipulates the behavior of cells. Herein, metabolic glycoengineering (MGE) is an easy but powerful technology for remodeling the structure of glycan. By presenting unnatural glycans on the surface, MGE provides us an opportunity to reshape the microenvironment and evoke desired cellular responses. In this review, we firstly focused on the determining role of glycans on cellular activity; then, we introduced how MGE influences glycosylation and subsequently affects cell fate; at last, we outlined the application of MGE in regenerative therapy, especially in the musculoskeletal system, and the future direction of MGE is discussed.

In-vitro seeding of human umbilical cord vein endothelial cells on hydroxyapatite for mechanical heart valve applications.

BACKGROUND AND AIM OF THE STUDY: Although heart valve replacement with either a mechanical or biological prosthesis is an effective method to treat valvular heart disease, both approaches have limitations, including thrombus formation, thromboembolism and degeneration problems. The study aim was to demonstrate the in-vitro endothelialization of hydroxyapatite (HAp) to be used as a biomaterial in heart valve prostheses. METHODS: The HAp samples were characterized using X-ray diffractometry to identify the crystalline phase, while the surface morphology of HAp discs was examined using scanning electron microscopy (SEM). Human umbilical vein endothelial cells (HUVECs) were cultured on HAp discs for 1, 3, 5, and 7 days, and on pyrolytic carbon discs for 7 days; cytotoxicity was assessed using the methyl thiazolyl tetrazolium (MTT) assay. The cells were incubated in three groups: (i) an experimental group (cultured with HAp extract); (ii) a negative control (cultured with high-density polyethylene chaff); and (iii) a positive control (culture medium containing 0.1% phenol solution). RESULTS: A morphological examination of the HAp discs revealed the presence of micropores on the disc surface, together with cultured HUVECs. After seven days of culture, the HUVECs began to form a confluent endothelial cell layer covering the HAp discs. There were no visible cells attached to the pyrolytic carbon surface. The MTT assay indicated that HAp did not exert any cytotoxic effect on HUVECs, and low optical density values were obtained in the positive controls. CONCLUSION: The study results showed that HUVECs were able to grow well on HAp discs, and that HAP possessed a good in-vitro bioactivity and biocompatibility towards these cells. Consequently, HAp might be used as a film on mechanical heart valve prostheses, and serve as a promising biomaterial for heart valve replacement.

Severe gastroparesis causing postoperative respiratory complications in a heart-lung recipient.

Heart-lung transplantation is reserved for selected patients who have end-stage cardiac and pulmonary disease. Gastroparesis, which is associated with aspiration, is commonly seen after transplantation. Here, we present a case in which gastric contents aspiration leads to Pseudomonas aeruginosa pulmonary infection, 11 months after the heart lung transplantation. We strongly recommend that early diagnosis and aggressive management of post-transplantation gastroparesis is essential to prevent lung allograft injury and pulmonary infections.

Cytotoxicity evaluation of hydroxyapatite on human umbilical cord vein endothelial cells for mechanical heart valve prosthesis applications.

BACKGROUND: Valvular heart disease is a significant cause of morbidity and mortality worldwide. Artificial heart valves are currently the most widely accepted biomedical material. However, the material's blood compatibility is still not sufficient. Biomaterial with a good biocompatibility has not yet appeared. Our initial study was to evaluate the probable cytotoxicity of hydroxyapatite (HA) on human umbilical vein endothelial cells (HUVEC) for mechanical heart valve prosthesis applications. METHODS AND RESULTS: Cell growth was tested by MTT assay and the cell relative growth rate (RGR) was calculated. Cells were cultured in media consisting of either leaching extracts of hydroxyapatite at 37 degrees C or leaching extracts at 121 degrees C or a negative and a positive control group, respectively. The cytotoxicity was graded using generally accepted standards. The RGR of cell lines cultured in the culture media consisting of either normal or heat temperature leaching extracts of hydroxyapatite and the negative controls were higher than in the positive controls. For 24 h, 48 h, and 72 h cultures, the cytotoxicity grade of HA was 0 in the normal temperature leaching extracts of hydroxyapatite and 1 in the heat temperature leaching extracts of hydroxyapatite. CONCLUSIONS: Human umbilical cord endothelial cells grew well in the HA extracts. Our results indicate that HA possesses good IN VITRO bioactivity and biocompatibility with human umbilical cord endothelial cells and could be used as film on mechanical heart valve prostheses.

Outcome of heart transplantations done in our centre.

BACKGROUND: We have found no study conducted economic issues on patient outcomes after heart transplantation (HTx) in China for further development. MATERIAL/METHODS: From May 2004 to February 2006, there were 10 transplants performed in 9 male patients in our center: 1 heart lung recipient and 8 heart recipient. Among them, 7 lacked health insurance and 2 had insurance. RESULTS: Their ages were between 24 years and 43 years (mean 39 years). The number of hospitalizations, number of days in hospital per admission, number of emergency room visits and mean left ventricular ejection fraction (LVEF) in the year before operation were 5.5, 54, 8.1 and 0.19 respectively. After operation, these figures decreased significantly to 1.7 (P<0.05), 18 (P<0.05), 1.1 (P<0.05) and 0.70 (P<0.05) respectively. During the follow up of 370~930d, one of the 9 patients who lacked health insurance died of acute rejection due to stopping mycophenolate mofetil (MMF) 7 months after operation and the heart lung recipient who also lacked health insurance died of pulmonary infection 1 year later. All patients who lacked health insurance experience emotional distress. CONCLUSIONS: HTx is a good treatment for selected patients with end-stage heart failure (ESHF) and future research is to be expected in the fields of insurance coverage to improve the quality of life and the Chinese transplant group should be commended for their courageous work in the treatment of end stage heart disease under challenging circumstances.