Objective To review the advance in the experimental studies of microRNA(miRNA) and the relationship between miRNA and stem cells. Methods The related literature was reviewed, and the research findings of miRNA and stem cell were summarized. Results miRNA was noncoding small RNA (20-25 nt) involved in posttranscriptional change, that have been shown to regulate gene expressions. Ithas been reported that some kinds of miRNAs were likely important regulators forstem cells maintaining their state of selfrenewal，and play key roles in theirdifferentiation. Conclusion miRNA as regulation of gene expressions, can be served as a new way for stem cells research.
Objective To investigate the viability and the characters of proliferation and differentiation of retinal stem cells (RSCs) after cryopreservation and anabiosis. Methods The RSCs of a Long Evans rat with the embryonic age of 17 days were separated and cultured in vitro. The third-passage RSCs in the cryopreservation liquid consisted of 80% Dulbecco modified Eagle medium (DMEM)/F12，10% bovine serum albumin (BSA)，10% dimethylsulfoxide (DMSO)，and basic fibroblast growth factor (bFGF) (20 ng/ml), were stored in liquid nitrogen. After 1, 2, 4, 8, 12, and 16 weeks of freezing period, these cells were thawed. The livability of the cells was counted and the differentiation was induced while the proliferation and characters of differentiation were detected by immunofluorescence. Results The effects of different durations of cryopreservation on the livability of RSCs did not differs much (Pgt;0.05). These cells were reculturd well and presented specific marker of RSCs. In addition, they also could be induced and differentiated into several types of retinal cells. Conclusion Cryopreservation and anabiosis of RSCs does not affect the cellular intrinsic characters of proliferation and differentiation. (Chin J Ocul Fundus Dis, 2007, 23: 94-97)
Objective To investigate the possibility of commitment differentiation of embryonic stem cells induced by the medium of cultured retinal neurons of SD rats. Methods The medium from cultured retinal neurons of SD rats were collected, sterilized and mixed with DMEM medium according to 2∶3 proportion, ES cells were cultured with these mixed medium and were observed under the phase contrast microscope daily, the induced cells were identified by NF immunohistochemistry methods. Results The ES cells cultured with these mixed medium can differentiate into neuron-like structure, and the induced cells were positive in NF immunofluorescence staining. Conclusion The medium from cultured retinal neurons of SD rats can induce ES cells commitment differentiation into neuron-like structure. (Chin J Ocul Fundus Dis, 2002, 18: 134-136)
OBJECTIVE To explore the possible mechanisms of skin regeneration through the epidermal stem cells stimulated by epidermal growth factor (EGF). METHODS At 8 and 14 days after treatment with EGF, the tissue specimens from 8 skin ulcered patients who were treated with EGF were used to evaluate the distribution and differentiation of epidermal stem cells. The expression of beta 1 integrin, keratin 19 (K19), keratin 14(K14) and keratin 10 (K10) in skin was detected with SP immunohistochemical methods. Hematoxylin and eosin staining method were used to observe the tissue structure. Another 7 biopsies from ulcered patients without EGF management were used as the control. RESULTS The results from the hematoxylin and eosin staining showed that the epidermis in EGF treated wounds was thick and the epidermal ridges were enlarged both in 8 and 14 days compared with those in control skin. Immunohistochemical staining from beta 1 integrin and K 19 showed that all tissues treated with EGF were rich in epidermal stem cells both in 8 and 14 days. These stem cells were bigger in size and larger in number and localized at the base of the epidermis. In contrast, the positive expression cells of beta 1 integrin and K 19 in control group in the same time were scanty. It was found that there were some stem cell islands in epidermis treated with EGF in day 14 and absent from the control group. The expression of K14 and K10 could be observed in those terminally differentiating epidermal cells in both groups. CONCLUSION The results indicate that the possible mechanisms of skin regeneration stimulated by EGF comes from the mitogenic effects and differentiation of skin stem cells.
Objective To study the effect of different types of supernatants fluid of retinal cells on the physiological function of neuron cells derived from embryonic stem cells. Methods Embryonic bodies were sub-induced by retinoic acid (group A), retinoic acid with the supernatant fluid of retinal glia cells and neurons of mouse (group B), retinoic acid with the supernatant fluid of fetal retinal glia cells (group C), respectively. The Sodium ion channels on the cytomembrane in the 3 groups were analyzed 5-21 days after the inducement. Results The sodium current in each group didn't change much 5-21 days after the inducement. The sodium channels presented burst-opening discharge in group A, brief-opening discharge in group B, and long-opening discharge in group C. The percentage of the cells without current in group A, B and C was 25%, 11.4%, and 23.8%, respectively, but the difference was not significant among the 3 groups(Pgt;0.05). The number of cells with sodium current increased at first and decreased later in group A, continuously increased in group B, and decreased at first and kept stable later in group C. The open time of sodium channels was the longest in group A, and the shortest in group B. The distribution of open time in the three groups could be managed with two-step exponential fit. Conclusion The supernatant fluid of retinal cells has apparent influence on the physiological function of the neuron cells derived from embryonic stem cells. (Chin J Ocul Fundus Dis, 2007, 23: 91-93)
Magneticaly labeled stem cells and magnetic resonance imaging(MRI) technology is an effective tracking method in vivo study, which has high spatial-temporal resolution. Gadolinium, which shows positive T1 signals and iron oxide showing negative T2 signals are the two often used contrast agents. The latter also include superparamagnetic iron oxide particle and ultrasmall superparamagnetic iron oxide particle. Transfection agents, e.g. poly-L-lysine and protamine sulfate，can enhance magnetical nanoparticles labeling stem cells. The biological characteristics of labeled stem cells did not seem to be altered. MRI can detect the labeled stem cells’ signals and also can track changes of signal in intensity and size with time past. In conclusion, MRI tracking magneticaly labeled stem cells represents a method for noninvasivly monitoring the existence and migration of engrafts.
Purpose To investigate the development of embryonic stem cells (ESC)in the subretinal space． Methods ESC were cultivated in suspension for 4 days till they developed into cell aggregates,i.e.embryonic body(EB).ESC as well as EB combined with or without RA were respectively transplanted into vitreous cavity and subretina1 space in SD rats,and the subretinal transplanted eyes,transient ischemia-reperfusion injuries were made by ligating the ophthalmic artery for 40 seconds before the transplantation .The experimental eyes were enucleated for histological and immunohistochemical assays after 14～28 d. Results The EB was found to develope into photoreceptors induced by RA in the subretinal space under an ischemia-reperfusion condition，and EB transplantation without RA induction induced multiple differentiations in the subretinal space.The single injection of RA without EB induced hyperplasia of the neural retinal cells.ESC transplanted into vitreous cavity rapidly proliferated and developed into atypical hyperplastic mass. Conclusion EB derived from ESC can differentiate into photoreceptors induced by RA in the host subretinal space under an ischemia-reperfusion condition. (Chin J Ocul Fundus Dis，2000，16：213-284)
Objective To summary the characteristics of adult stem cells and to introduce the definition and the features of stem cell disease.Methods Literature concerning adult stem cells and stem cell disease was extensively reviewed.Results Adult stem cells were localized in tissues and organs, and were able to generate function cells to replace cell loss during a lifetime of wear and tear. The stem cells had selfrenewal to maintain themselves and undergo aging within the lifespan of an organism. The dysfunction of stem cells was capable to cause diseases, which could be defined as stem cell disease in human. The disorder of self renewal and differentiation in stem cells could increase the cellular proliferation, produce proliferative diseases such as tumors. The stem cells with self renewal defect, differentiation blockage, or aged stem cells could not supply enough function cells for tissue refreshment. The defect of tissue refreshment caused degenerative diseases.Conclusion Studies on the stem cell self renew, differentiation, and aging can provide knowledge to understand the mechanism of stem cell diseases and develop technique to diagnose and treat these diseases.
Objective To review the status and appl ication prospect in repair of spinal cord injury by stem cells. Methods The related articles in recent years were extensively reviewed, the biological characteristics of stem cells, the experimental and cl inical studies on repair of spinal cord injury by stem cells, the mechanism of the therapy and the problem were discussed and analyzed. Results The foundational and cl inical study indicated that the great advance was made in repair of spinal cord injury, the stem cells could immigrate in the spinal cord, and differentiate into neuron and secrete neurotrophic factors. So it could promote the repair effects. Conclusion Repair of spinal cord injury by stem cells is an effective therapystrategy, but many problems remain to be resolved.
Objective To investigate the latest development of tissue engineeredregenerative medicine in industrialization, with the intention to direct work in practical area. Methods A complete insight of regenerative medicine in industrialization was obtained through referring to update publications, visiting related websites, as well as learning from practical experience. Results The aerial view of the future of regenerative medicine was got based on knowledge of four different tissue engineering projects. Conclusion All present efforts should be devoted to regenerative medicine area meeting the industrialized trends.