Design of a three-dimensionally controlled multi-cell-assembly system based on the control of a mixer nozzle / 生物医学工程学杂志

Three-dimensionally controlled cell-assembly technique makes fabricating tissues and organs in vitro to be possible. However, for real tissues and organs with complex structure and various cells, fabricating tissues and organs in vitro need a technique that could assemble and locate multi cells and materials precisely in the space. Facing the needs of multi-cell assembly, we designed a mixer nozzle and the matching pulse switching circuit which based on the single-nozzle cell assembly system, and developed a multi-cell-assembly system. We also carried out some assembly experiments with this system using materials that were similar to the multi-component extracellular matrix materials. The results demonstrated that the system could assemble various cells and materials into three-dimensional inhomogeneous structures precisely.

Recombinant human growth hormone secreted from tissue-engineered bioartificial muscle improves left ventricular function in rat with acute myocardial infarction / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Experimental studies and preliminary clinical studies have suggested that growth hormone (GH) treatment may improve cardiovascular parameters in chronic heart failure (CHF). Recombinant human GH (rhGH) has been delivered by a recombinant protein, by plasmid DNA, and by genetically engineered cells with different pharmacokinetic and physiological properties. The present study aimed to examine a new method for delivery of rhGH using genetically modified bioartificial muscles (BAMs), and investigate whether the rhGH delivered by this technique improves left ventricular (LV) function in rats with CHF.</p><p><b>METHODS</b>Primary skeletal myoblasts were isolated from several Sprague-Dawley (SD) rats, cultured, purified, and retrovirally transduced to synthesize and secrete human rhGH, and tissue-engineered into implantable BAMs. Ligation of the left coronary artery or sham operation was performed. The rats that underwent ligation were randomly assigned to 2 groups: CHF control group (n = 6) and CHF treatment group (n = 6). The CHF control group received non-rhGH-secreting BAM (GFP-BAMs) transplantation, and the CHF treatment group received rhGH-secreting BAM (GH-BAMs) transplantation. Another group of rats served as the sham operation group, which was also randomly assigned to 2 subgroups: sham control group (n = 6) and sham treatment group (n = 6). The sham control group underwent GFP-BAM transplantation, and the sham treatment group underwent GH-BAM transplantation. GH-BAMs and GFP-BAMs were implanted subcutaneously into syngeneic rats with ligation of the left coronary artery or sham operation was performed. Eight weeks after the treatment, echocardiography was performed. hGH, insulin-like growth factor-1 (IGF-1) and TNF-alpha levels in rat serum were measured by radioimmunoassay and ELISA, and then the rats were killed and ventricular samples were subjected to immunohistochemistry.</p><p><b>RESULTS</b>Primary rat myoblasts were retrovirally transduced to secrete rhGH and tissue-engineered into implantable BAMs containing parallel arrays of postmitotic myofibers. In vitro, they secreted 1 to 2 microg of bioactive rhGH per day. When implanted into syngeneic rat, GH-BAMs secreted and delivered rhGH. Eight weeks after therapy, LV ejection fraction (EF) and fractional shortening (FS) were significantly higher in CHF rats treated with GH-BAMs than in those treated with GFP-BAMs ((65.0 +/- 6.5)% vs (48.1 +/- 6.8)%, P < 0.05), ((41.3 +/- 7.4)% vs (26.5 +/- 7.1)%, P < 0.05). LV end-diastolic dimension (LVEDD) was significantly lower in CHF rats treated with GH-BAM than in CHF rats treated with GFP-BAM (P < 0.05). The levels of serum GH and IGF-1 were increased significantly in both CHF and sham rats treated with GH-BAM. The level of serum TNF-alpha decreased more significantly in the CHF treatment group than in the CHF control group.</p><p><b>CONCLUSIONS</b>rhGH significantly improves LV function and prevents cardiac remodeling in rats with CHF. Genetically modified tissue-engineered bioartificial muscle provides a method delivering recombinant protein for the treatment of heart failure.</p>

In vitro study of regulation of shear stress on antithrombogenic potentials of endothelialized polyurethane small diameter artificial blood vessel / 生物医学工程学杂志

This study was designed to investigate the changes of prostaglandin I2 (PGI2) and nitric oxide (NO) secreted by endothelialized polyurethane small diameter artificial blood vessel. The peripheral blood mononuclear cells of healthy adult were separated and induced into endothelial progenitor cells (EPCs), which were identified by the methods of discrepancy microphage and fluorescent immunology labeling. After the induced cells being seeded on the polyurethane small-diameter artificial vessels, the endothelialized polyurethane small diameter artificial blood vessels were divided into four different experimental groups, including stationary group, low-flow shear stress group (5 dynes/cm2), medium-flow shearstress group (15 dynes/cm2), and high-flow shear stress group (25 dynes/cm2). Then, the levels of 6-ketoprostaglandin F1alpha (6-keto-PGF1alpha) and NO of different time were measured by enzyme-linked immunosorbent assay and nitrate reductase methods. The peripheral blood mononuclear cells differentiated into EPCs. They presented typical "spindie-shaped" appearance, and they were positively labeled by fluorescent acetylated-LDL, lectin, FLK-1 and vWF. Shear stress enhanced the production of NO and 6-keto-PGF1alpha by EPCs in a dose-dependent manner. Therefore, shear stress increases the secretion of NO and PGI2 by EPC, which suggests that shear stress can improve the antithrombogenic potentials of endothelialized polyurethane small diameter artificial blood vessel.

Research and development of artificial retina material / 生物医学工程学杂志

The application of artificial retina was introduced. The principal characteristics of artificial retina material were reviewed in particular. Moreover, the recent research development and application prospect were discussed.

In vitro study of seeding of peripheral blood endothelial progenitor cells on endothelialized polyurethane small diameter artificial blood vessel and shear stress treatment / 生物医学工程学杂志

In this study, the peripheral blood mononuclear cells of healthy adult were acquired and inducted by vascular endothelial growth factor, et cetera. The differentiated endothelial cells were observed and identified as EPCs by the double positive staining of fluorescent labeled acetylated-LDL and lectin, seeded on the polyurethane small-diameter artificial vessels, treated by shear stress of 15 dyn/cm2, and observed by scanning electronic microscopy. As a result, the peripheral blood mononuclear cells differentiated into EPCs. They were positively stained by labeled acetylated-LDL and lectin. Under observation of scanning electronic microscope, the unseeded polyurethane small-diameter artificial vessel being suited for the growth and spreading of the cells; the cell lineage on surface of artificial vessels of stationary group being arrayed in chaos, and that of shear stress group being arrayed in direction. Therefore, the peripheral cells can differentiate into EPCs, and EPCs can be used as novel source cells for the accelerated endothelialization of small diameter artificial vessel. Shear stress contributes to the mechanic moulding of cell lineage on the surface of artificial vessel.

Separation and purification of skeletal muscle satellite cells for tissue engineering applications by Percoll / 中国医学科学院学报

<p><b>OBJECTIVE</b>To investigate separation and purification of skeletal muscle satellite cells with improved incontinuous density Percoll gradient centrifugation technique.</p><p><b>METHODS</b>The primary skeletal muscle satellite cells of New Zealand white rabbits were cultured with different adhesion time method and incontinuous density Percoll gradient centrifugation technique. The cells were observed under invert microscope and scanning electron microscope. The degree of purification was examined by celluar immunochemical stain. The growth curve was tested by thiazolyl blue assay.</p><p><b>RESULTS</b>Over 90% satellite cells were harvested by incontinuous density Percoll gradient centrifugation technique, in contrast to which, only 30%-40% cells were harvested by different adhesion time. Morphological observation accorded with satellite cells. The growth curve indicated that the cells grew in a good status.</p><p><b>CONCLUSION</b>The high purification satellite cells can be obtained by incontinuous density Percoll gradient centrifugation technique. It is a good method to culture seed cells for tissue engineering applications.</p>

Primary experimental study on the construction of tissue engineering blood vessel / 中华外科杂志

<p><b>OBJECTIVE</b>To explore the primary experimental methods to construct tissue engineering blood vessel.</p><p><b>METHODS</b>Using the collagen-chitosan to prefabricate the scaffolds with 3-dimensional structure, the proliferated human endothelial cells (ECs), smooth muscle cells (SMCs) and fibroblasts act as the seed cells. The cells were seeded to scaffolds in two-step method, and engineering tissue were matured by static culture or bioreactor culture. Extracellular matrix contents and the platelet aggregation were examined in engineering tissue, tissue engineering blood vessels were taken as patches to repair the man-made defaults on the rats aorta.</p><p><b>RESULTS</b>The proliferated human ECs, SMCs and fibroblast can hold activity and act as seed cells. The prefabricated scaffolds, with excellently cell and tissue biocompatibility, can facilitated cells adherence and upgrowth, the cells quantities and extracellular matrix contents in engineered tissue are time dependent increase (P < 0.05). Platelet aggregation tests confirm the tissue engineering blood vessel have some anti-coagulability. Using the engineering tissue patch to repair the default, 6 aortas in 8 animal were patency till 10 days post-operation.</p><p><b>CONCLUSIONS</b>The seeding cells can be seeded on the 3-dimensional collagen-chitosan scaffolds and matured, the tissue engineering blood vessel can be constructed primarily.</p>

Research advances of small-diameter vascular grafts / 中国医疗器械杂志

This review is a summary of some useful methods and advances about improving clinical applications to small-diameter vascular grafts in recent years, and it points out the developing orientation of small-diameter vascular grafts in the future.

Progress in studies of tissue-engineered heart valves / 生物医学工程学杂志

Valve replacement represents the most common surgical therapy for valvular heart diseases. However, the long-term results of the valve protheses in clinical use are not satisfying. Recently, with the development of tissue engineering, more and more studies are focusing on creating ideal valve substitutes through seeding autologous cells on biodegradable scaffold. This article describes the definition of valvular tissue engineering, the choice of scaffold biomaterials, the methods of cell culture and seeding, and the evaluation of tissue-engineered heart valves. Furthermore, the problems which should be resolved in the future are also presented in the article.

Application of tissue engineering in bioartificial renal tubule / 生物医学工程学杂志

Tissue engineering is a discipline involving both materials science, engineering and life science. It has found successful application in Bioartificial renal tubule assist device RAD which is still under development. Experiments have proved that RAD can serve as renal tubule to perform its transport, metabolic and endocrine functions in patients with acute or chronic renal failure.