Morphological study on the growth of human amniotic membrane loaded with porcine bone marrow-derived mesenchymal stem cells / 中国组织工程研究

ABSTRACT

BACKGROUND: Human amniotic membrane (HAM) contains various ingredents such as collagen, glycoprotein,proteoglycan, integrin and laminated body, and so on, and expresses many kinds of growth factors and mRNA-associated proteins. And these ingredents can supply abundant nutriments for cellular proliferation and differentiation, and benefit cells to grow and propagate. Whether or not HAM can load porcine bone marrow-derived mesenchymal stem cells (BMSCs) to well grow on it deserves to be further investigated.OBJECTIVE: To set up a method of tissue engineering of human amniotic membrane loading porcine BMSCs and observe the morphological characteristics of growth and proliferation of BMSCs seeded on HAM.DESIGN: Randomized controlled observation.SETTING: State Key Laboratory of Trauma, Burn and Combined Injury, General Institute of Combined Injuries, Academy of Preventive Medicine, Third Military Medical University of Chinese PLA.MATERIALS This experiment was carried out in the State Key Laboratory of Trauma, Burn and Combined Injury,General Institute of Combined Injuries, Academy of Preventive Medicine, Third Military Medical University of Chinese PLA between January and November 2003. Three Guizhou minipigs of either gender, aged 2 to 3 months, weighing from 6 to 8 kg, were provided by the Experimental Animal Center, Third Military Medical University of Chinese PLA. Main reagentISCOVE'S modified DULBECCO'S medium (IMDM) culture medium (Hyclone, USA); high-quality fetal bovine serum PAA (Germany); haematoxylin (China); Eosin B (Sigma, USA) and OCT embedding medium (USA). Main instruments BX51 stereoscopic fluorescence microscope (Olympus, JaPan); IX70 inverted fluorescence microscope (Olympus, Japan);cryostat (2700-Frigcut, Germany); myeloid puncture needle (Jiangsu); superclean bench (Sujing Bloc Antai Company);CO2 constant-temperature incubator (QUEUE, USA).METHODS: HAM was prepared as previously described. The BMSCs of Guizhou minipigs isolated and cultured according to method described previously were primarily cultured and passaged, then they were inoculated to the stromal surface of HAM at different densities (0.84×105 cells/cm2,1.54×105 cells/cm2,2.75×105 cells/cm2); The growth and proliferation of BMSCs of different densities were observed under an inverted microscope and scanning electron microscope; BMSCs of the second or the third passages were inoculated on HAM held with tissue-holding device at a density of 1.54×105 cells/cm2, and they were cultured for 18 days at most. The HAM was daily rolled, sliced and stained by HE for observing the growth of BMSCs loaded on HAM under the light, scanning and transmission electron microscopes.MAIN OUTCOME MEASURES: The growth of BMSCs on HAM was examined at different densities and different time points.RESULTS: ① Comparison of growths of BMSCs promoted by different densities of HAM BMSCs,which were planted on HAM at the density of 0.84×105 cells/cm2 were irregular and scattered under an invert microscope. Distances between BMSCs were biggish. BMSCs seeded on HAM at the density of 1.54×105 cells/cm2 were regular in arrangement and moderate in density, with clear cell outline and good cell activity before 24 hours, and seeded at the density of 2.75×105 cells/cm2 were congested with many nonattached cells and the longer the growing time of the cells was, the more the cellular debris were observed. BMSCs,which were planted on HAM at the density of 0.84×105 cells/cm2 under the scanning electron microscope, scatted on HAM presented in shapes of irregular, long, thin and flat polygon. Their membrane protuberances presented in shapes of thick and thin, and the distances between cells were biggish. BMSCs,which were planted on HAM at the density of 1.54×105 cells/cm2 have similar appearance of their bodies and membrane protuberances, and the membrane protuberances were more compared with the BMSCs planted at the density of 0.84×105 cells/cm2. Their membrane protuberances intercrossed each other, and the margin of some BMSCs overlapped each other. BMSCs planted at the density of 2.75×105 cells/cm2, arraved on HAM crowdedly and overlappedly with many debris. Their membrane protuberances were not obviously. The margin of some BMSCs was overlapped.② Comparisonof growths of BMSCs promoted by HAM at different time points Under the inverted microscope, the BMSCs adhered quickly to HAM after being incubated for about 30 minutes. All of BMSCs adhered to HAM within 24 hours, and formed monolayer on it within 48 hours, and grew densely on HAM after being cultured for 4 to18 days. Under the light and electron microscopes, HE results revealed that BMSCs adhered tightly and grew on HAM in different arrays, such as emitting, whirlpool or parallel,and their nuclei located in middle, dense in staining, were big and clear. The shapes of BMSCs were comparatively consistent on HAM. HAM loaded with BMSCs grew 4 days, and BMSCs covered HAM completely. The densities of BMSCs on HAM were suitable, and their bodies were large, and presented irregular, long,thin and flat polygon under the scanning electron microscope. The margin of some BMSCs overlapped each other. The protuberances of cellular membrane of BMSCs were abundant in the shapes of thick and thin. Some protuberances intercrossed each other in the shape of net. BMSCs adhered tightly to HAM through these protuberances. HAM loading BMSCs grow 4 days; most of BMSCs grew on HAM in double layers with the shapes of cambiform under the transmission electron microscope, Their nucleoli were clear. The protuberances of cellular membrane of BMSCs, which situated at two sides of nuclei and overlapped each other, were long. Most of chromatins of BMSCs were autosome.Abundant organell such as rough endoplasmic reticulum (RER),mitochondria could be observed in BMSCs.CONCLUSION:HAM is able to promote the proliferation of BMSCs significantly. BMSCs may be cultured on HAM ex vivo.HAM is a good carrier of BMSCs.