Molecular imaging of induced pluripotent stem cell immunogenicity with in vivo development in ischemic myocardium.

Whether differentiation of induced pluripotent stem cells (iPSCs) in ischemic myocardium enhances their immunogenicity, thereby increasing their chance for rejection, is unclear. Here, we dynamically demonstrated the immunogenicity and rejection of iPSCs in ischemic myocardium using bioluminescent imaging (BLI). Murine iPSCs were transduced with a tri-fusion (TF) reporter gene consisting of firefly luciferase-red fluorescent protein-truncated thymidine kinase (fluc-mrfp-tTK). Ascorbic acid (Vc) were used to induce iPSCs to differentiate into cardiomyocytes (CM). iPSCs and iPS-CMs were intramyocardially injected into immunocompetent or immunosuppressed allogenic murine with myocardial infarction. BLI was performed to track transplanted cells. Immune cell infiltration was evaluated by immunohistochemistry. Syngeneic iPSCs were also injected and evaluated. The results demonstrated that undifferentiated iPSCs survived and proliferated in allogenic immunocompetent recipients early post-transplantation, accompanying with mild immune cell infiltration. With in vivo differentiation, a progressive immune cell infiltration could be detected. While transplantation of allogenic iPSC-CMs were observed an acute rejection from receipts. In immune-suppressed recipients, the proliferation of iPSCs could be maintained and intramyocardial teratomas were formed. Transplantation of syngeneic iPSCs and iPSC-CMs were also observed progressive immune cell infiltration. This study demonstrated that iPSC immunogenicity increases with in vivo differentiation, which will increase their chance for rejection in iPSC-based therapy.

The influence of chitosan hydrogel on stem cell engraftment, survival and homing in the ischemic myocardial microenvironment.

One challenge of cellular cardiomyoplasty for myocardial infarction (MI) is how to improve MI microenvironment to facilitate stem cell engraftment, survival and homing for myocardial repair. The application of injectable hydrogels is an effective strategy. However, it has not been thoroughly investigated on the role of the injectable scaffolds, in improving MI microenvironment, providing space and guidance for cell survival, engraftment and homing. We explored an injectable chitosan hydrogel for stem cell delivery into ischemic heart and investigated the beneficial effects and mechanisms of the hydrogel. In vitro, H(2)O(2)-treatment was used to mimic reactive oxygen species (ROS) microenvironment. The influence of ROS and protection of chitosan components on adipose-derived mesenchymal stem cells (ADSCs) was analyzed too. In vivo, MI was induced by the left anterior descending artery ligation in SD rats. PBS, chitosan hydrogel, ADSC/PBS and ADSC/chitosan hydrogel were injected into the border of infracted hearts respectively. Multi-techniques were used to assess the beneficial effects of chitosan hydrogel after transplantation. We observed that ROS generated by ischemia would impair ADSC adhesion molecules, including integrin-related adhesion molecules integrin αV and ß1, focal adhesion-related molecules p-FAK and p-Src, and corresponding ligands of host myocardium ICAM1 and VCAM1. Chitosan hydrogel could rescue these molecules through ROS scavenging and recruit key chemokine for stem cell homing, such as SDF-1. The results suggest that chitosan hydrogel could improve MI microenvironment, enhance stem cell engraftment, survival and homing in ischemic heart through ROS scavenging and chemokine recruitment, contributing to myocardial repair.

Injectable biodegradable hydrogels for embryonic stem cell transplantation: improved cardiac remodelling and function of myocardial infarction.

In this study, an injectable, biodegradable hydrogel composite of oligo[poly(ethylene glycol) fumarate] (OPF) was investigated as a carrier of mouse embryonic stem cells (mESCs) for the treatment of myocardial infarction (MI). The OPF hydrogels were used to encapsulate mESCs. The cell differentiation in vitro over 14 days was determined via immunohistochemical examination. Then, mESCs encapsulated in OPF hydrogels were injected into the LV wall of a rat MI model. Detailed histological analysis and echocardiography were used to determine the structural and functional consequences after 4 weeks of transplantation. With ascorbic acid induction, mESCs could differentiate into cardiomyocytes and other cell types in all three lineages in the OPF hydrogel. After transplantation, both the 24-hr cell retention and 4-week graft size were significantly greater in the OPF + ESC group than that of the PBS + ESC group (P < 0.01). Four weeks after transplantation, OPF hydrogel alone significantly reduced the infarct size and collagen deposition and improved the cardiac function. The heart function and revascularization improved significantly, while the infarct size and fibrotic area decreased significantly in the OPF + ESC group compared with that of the PBS + ESC, OPF and PBS groups (P < 0.01). All treatments had significantly reduced MMP2 and MMP9 protein levels compared to the PBS control group, and the OPF + ESC group decreased most by Western blotting. Transplanted mESCs expressed cardiovascular markers. This study suggests the potential of a method for heart regeneration involving OPF hydrogels for stem cell encapsulation and transplantation.

Research for the effect of octylphenol on spermatogenesis and proteomic analysis in octylphenol-treated mice testes.

OP (octylphenol), an environmental oestrogen was administered, and differentially expressed proteins were analysed in mice testes to clarify its mechanism of action in male sterility. Male Kunming suckling mice (10 days old) were subcutaneously injected with OP at a dose of 10 µg/kg per day, 50 µg/kg per day and 100 µg/kg per day as low-, medium- and high-dose groups, respectively, for 35 days. Animals in the control group received subcutaneous injections of olive oil at a dose of 10 µl/mouse per day. Serum oestradiol, testosterone, FSH (follicle stimulating hormone) and LH (luteinizing hormone) levels were measured on day 45. The left testes were removed for tissue analysis, and the right testes were analysed for differentially expressed proteins by using two-dimensional gel electrophoresis and MS. Tissue analysis showed that mice spermatogenesis was blocked at the round spermatid stage in the high-dose group, whereas no such changes were found in the medium- and low-dose groups. Higher serum oestradiol (P<0.05) and lower testosterone (P<0.05) levels were found in the medium- and high-dose groups. There was no significant difference in serum oestradiol and testosterone levels in the low-dose and control groups. No significant influence of OP was seen on serum FSH and LH levels in all OP-treated animals. The results from four differentially expressed proteins such as PPIA (peptidyl-prolyl cis-trans isomerase A), PEBP1 (phosphatidylethanolamine-binding protein1), TPI (triose-phosphate isomerase) and TCP-1 (T-complex protein 1) in the high-dose and control groups showed up-regulation of PPIA expression and down-regulation in PEBP1, TPI and TCP-1 expressions. These findings will contribute to clarify the mechanism of male sterility by environmental oestrogens.

Telocytes accompanying cardiomyocyte in primary culture: two- and three-dimensional culture environment.

Recently, the presence of telocytes was demonstrated in human and mammalian tissues and organs (digestive and extra-digestive organs, genitourinary organs, heart, placenta, lungs, pleura, striated muscle). Noteworthy, telocytes seem to play a significant role in the normal function and regeneration of myocardium. By cultures of telocytes in two- and three-dimensional environment we aimed to study the typical morphological features as well as functionality of telocytes, which will provide important support to understand their in vivo roles. Neonatal rat cardiomyocytes were isolated and cultured as seeding cells in vitro in two-dimensional environment. Furthermore, engineered myocardium tissue was constructed from isolated cells in three-dimensional collagen/Matrigel scaffolds. The identification of telocytes was performed by using histological and immunohistochemical methods. The results showed that typical telocytes are distributed among cardiomyocytes, connecting them by long telopodes. Telocytes have a typical fusiform cell body with two or three long moniliform telopodes, as main characteristics. The vital methylene blue staining showed the existence of telocytes in primary culture. Immunohistochemistry demonstrated that some c-kit or CD34 immuno-positive cells in engineered heart tissue had the morphology of telocytes, with a typical fusiform cell body and long moniliform telopodes. Also, a significant number of vimentin+ telocytes were present within engineered heart tissue. We suggest that the model of three-dimensional engineered heart tissue could be useful for the ongoing research on the functional relationships of telocytes with cardiomyocytes. Because the heart has the necessary potential of changing the muscle and non-muscle cells during the lifetime, telocytes might play an active role in the heart regeneration process. Moreover, telocytes might be a useful tool for cardiac tissue engineering.

Both the transplantation of somatic cell nuclear transfer- and fertilization-derived mouse embryonic stem cells with temperature-responsive chitosan hydrogel improve myocardial performance in infarcted rat hearts.

The transplantation of embryonic stem cells could improve cardiac function but was limited by immune rejection as well as low cell retention and survival within the ischemic tissues. The somatic cell nuclear transfer (SCNT) is practical to generate autologous histocompatible stem (nuclear-transferred embryonic stem [NTES]) cells for diseases, but NTES may be arguably unsafe for therapeutic application. The temperature-responsive chitosan hydrogel is a suitable matrix in cell transplantation. As the scaffold, chitosan hydrogel was coinjected with NTES cells into the left ventricular wall of rat infarction models. Detailed histological analysis and echocardiography were performed to determine the structure and functional consequences of transplantation. The myocardial performance in SCNT- and fertilization-derived mouse ES cell transplantation with chitosan hydrogel was also compared. The results showed that both the 24-h cell retention and 4-week graft size were significantly greater in the NTES + chitosan group than that of NTES + phosphate-buffered saline (PBS) group (p < 0.01). The NTES cells might differentiate into cardiomyocytes in vivo. The heart function improved significantly in the chitosan + NTES group (fractional shortening: 28.7% +/- 2.8%) compared with that of PBS + NTES group (fractional shortening: 25.2% +/- 2.9%) at 4 weeks after transplantation (p < 0.01). In addition, the arteriole/venule densities within the infarcted area improved significantly in the chitosan + NTES group (280 +/- 17/mm(2)) compared with that of PBS + NTES group (234 +/- 16/mm(2)) at 4 weeks after transplantation (p < 0.01). There was no difference in the myocardial performance in SCNT- and fertilization-derived mouse ES cell transplantation with chitosan hydrogel. The NTES cells with chitosan hydrogel have been proved to possess therapeutic potential to improve the function of infarcted heart. Thus the method of in situ injectable tissue engineering is promising clinically.

Reconstruction of endometrium in vitro via rabbit uterine endometrial cells expanded by sex steroid.

OBJECTIVE: To culture rabbit endometrial cells by using sex steroids to provide adequate seeding cells for endometrium reconstruction and uterine tissue engineering. DESIGN: Prospective experimental study. SETTING: Beijing Institute of Basic Medical Sciences and Tissue Engineering Research Center, Academy of Military Medical Sciences. ANIMAL(S): New Zealand rabbit and Kunming white strain mice. INTERVENTION(S): Rabbits were primed with pregnant mare serum gonadotropin and hCG. Endometrial cells were cultured with E(2) and P(4) of different concentrations. The endometrium was reconstructed by using endometrial cells as seeding cells and collagen-basement membrane matrix as scaffolds. MAIN OUTCOME MEASURE(S): Assay with 93-(4,5-dimethylthiazol-2-yl)2,5-diphenyl tetrazolium bromide, immunofluorescence staining, flow cytometric analysis, hematoxylin and eosin and immunohistochemical staining, and developmental rate of embryos. RESULT(S): The expression patterns of estrogen receptor and P receptor of rabbit endometrium were different before and after treatment with pregnant mare serum gonadotropin-hCG. One hundred nanomolar E(2) with 10 nmol/L P(4) facilitated the proliferation of epithelial cells whereas 100 nmol/L P(4) facilitated that of stromal cells. The epithelial cells could be stable if cultured for seven or eight passages. Cells in the epithelial layer of the reconstructed endometrium were cytokeratin positive. Some showed columnar morphology akin to the luminal epithelium in vivo. Reconstructed endometrium could improve the developmental rate and quality of one-cell mice embryos. CONCLUSION(S): Rabbit endometrial cells could be cultured with a long-standing proliferation capability by sex steroids and applied in uterine tissue engineering. Reconstructed endometrium with proliferated endometrial cells was akin to native endometrium in structure and function.

Effects of colchicine or demecolcine on cytoplasmic protrusions and assisted enucleation of golden hamster oocytes.

To establish experimental protocols for cloning golden hamsters, optimal concentrations of colchicine and demecolcine were determined for inducing cytoplasmic protrusion (containing chromosomes) and assisting enucleation of their oocytes. Denuded oocytes at different ages were treated with 2.5-10 microg/ml of colchicine for 1-4h or 0.02-0.6 microg/ml of demecolcine for 15-60 min. Cytoplasmic protrusions of oocytes were removed with a micromanipulation pipette. The results show that: 1) at 13.5-18h post-hCG injection, approximately 90% of oocytes treated for with 10 microg/ml of colchicine formed cytoplasmic protrusions, and in some oocytes enucleation occurred; 2) when treated with 0.4 microg/ml of demecolcine for 1h, cytoplasmic protrusions 13.5-18h post-hCG treatment were present in almost all oocytes; 3) after the protrusions induced by either treatment had been removed, the assisted enucleation rate was >80%, whereas it was approximately 32% with blind enucleation.

Changes in the reciprocal position of the first polar body and oocyte chromosome set in golden hamsters.

The golden hamster is an attractive model organism for studying reproductive physiology, oncology, genetics and virology. In an effort to establish experimental protocols necessary for cloning golden hamsters, we examined changes in the reciprocal position of the FPB (first polar body) and chromosome set of MII (the second meiotic metaphase) oocytes of golden hamsters. Oocytes were collected under three different conditions: (i) oocyte direct recovery from the oviduct of hormonally treated donor; (ii) oocyte recovery from the oviduct of hormonally treated donor followed by 5 h/10 h in vitro culture; and (iii) oocyte recovery from ovaries of hormonally treated donors and in vitro maturation. Then oocyte recovery was performed from the oviduct of hormonally treated donors, followed by 5 h in vitro culture with colchicine and/or CB (cytochalasin B). Denuded oocytes were stained with Hoechst 33342 and propidium iodide and evaluated under a microscope. Our results demonstrate that the change in FPB position in relation to the MII oocyte chromosome set increases with age of in vivo-matured oocytes. Cumulus cells can protect the FPB of in vitro-cultured oocytes from degeneration but do not significantly affect its repositioning, and in vitro-matured oocytes age slower. The colchicine has a stronger effect on cytoplasmic protrusions of golden hamster oocytes when compared with CB. These results define conditions for changes in FPB position relative to the MII oocyte chromosome set. Early ovulated oocytes, in vitro-matured oocytes and oocytes treated with colchicine should improve the effectiveness of the cloning procedure in golden hamsters as an animal model for human diseases.

Reconstruction of engineered uterine tissues containing smooth muscle layer in collagen/matrigel scaffold in vitro.

OBJECTIVE: This study attempted to reconstruct engineered uterine tissues (EUTs) containing smooth muscle layer, akin to the normal uterine wall. METHODS: EUTs were reconstructed by seeding epithelial cells on top of the constructed stromal layer over smooth muscle layer. A self-made mold was used to keep the EUTs from contraction. At the same time, it provided static stretch to the EUTs. After 14 days of culture, the structure of the EUTs was analyzed histologically and immunohistochemically, or by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The expression of integrin beta3 subunit, heparin-binding epidermal growth factor (EGF)-like growth factor (HB-EGF), and HOXA-10 was detected by reverse transcription-polymerase chain reaction (RT-PCR). The ability of the EUTs supporting the development of embryos was estimated by coculturing embryos on the EUTs. We also tried a new method to reconstruct EUTs by mixing epithelial cell and stromal cells (1:2) in collagen/Matrigel to form an endometrial layer and putting it on top of the smooth muscle layer. The self-assembling ability of the endometrial epithelial cells and stromal cells in the reconstructed EUTs was analyzed histologically and immunohistochemically. RESULTS: The results found that the constructed EUTs with the first and the second method showed three-layered structures. The epithelial layer, stromal layer, and smooth muscle layer were stained by cytokeratin 18, vimentin, and alpha-actin, respectively. TEM showed that the cells in the EUTs reconstructed by the first method were attached to each other by apical tight junctions and rivet-like desmosomes. SEM showed protruded pinopodes, microvilli, and cilium of epithelial cells. The RT-PCR analysis showed that integrin beta3 subunit, HB-EGF, and HOXA-10 were expressed in EUTs. The coculture system of EUTs improved the development rate and quality of murine embryo significantly in comparison with those of control Chatot Ziomek Bavister culture. In the EUTs reconstructed by the second method, the epithelial cells demonstrated self-assembling ability and formed epithelial cell layer on top of the stromal layer and glandular tube-like structures in the stromal layer. Columnar epithelial cells existed in some parts of the epithelial layer. CONCLUSION: We engineered EUTs containing smooth muscle layer by two methods. The reconstructed EUTs could support the development of embryos. The epithelial cells showed self-assembling ability in the EUTs.

Functional improvement of infarcted heart by co-injection of embryonic stem cells with temperature-responsive chitosan hydrogel.

Transplantation of embryonic stem cells (ESCs) can improve cardiac function in treatment of myocardial infarction. The low rate of cell retention and survival within the ischemic tissues makes the application of cell transplantation techniques difficult. In this study, we used a temperature-responsive chitosan hydrogel (as scaffold) combined with ESCs to maintain viable cells in the infarcted tissue. Temperature-responsive chitosan hydrogel was prepared and injected into the infarcted heart wall of rat infarction models alone or together with mouse ESCs. The result showed that the 24-h cell retention and 4 week graft size of both groups was significantly greater than with a phosphate buffered saline control. After 4 weeks of implantation, heart function, wall thickness, and microvessel densities within the infarct area improved in the chitosan + ESC, chitosan, and ESC group more than the PBS control. Of the three groups, the chitosan + ESC performed best. Results of this study indicate that temperature-responsive chitosan hydrogel is an injectable scaffold that can be used to deliver stem cells to infarcted myocardium. It can also increase cell retention and graft size. Cardiac function is well preserved, too.

Bioreactor cultivation enhances NTEB formation and differentiation of NTES cells into cardiomyocytes.

Autogenic embryonic stem cells established from somatic cell nuclear transfer (SCNT) embryos have been proposed as unlimited cell sources for cell transplantation-based treatment of many genetic and degenerative diseases, which can eliminate the immune rejection that occurs after transplantation. In the present study, pluripotent nuclear transfer ES (NTES) cell lines were successfully established from different strains of mice. One NTES cell line, NT1, with capacity of germline transmission, was used to investigate in vitro differentiation into cardiomyocytes. To optimize differentiation conditions for mass production of embryoid bodies (NTEBs) from NTES cells, a slow-turning lateral vessel (STLV) rotating bioreactor was used for culturing the NTES cells to produce NTEBs compared with a conventional static cultivation method. Our results demonstrated that the NTEBs formed in STLV bioreactor were more uniform in size, and no large necrotic centers with most of the cells in NTEBs were viable. Differentiation of the NTEBs formed in both the STLV bioreactor and static culture into cardiomyocytes was induced by ascorbic acid, and the results demonstrated that STLV-produced NTEBs differentiated into cardiomyocytes more efficiently. Taken together, our results suggested that STLV bioreactor provided a more ideal culture condition, which can facilitate the formation of better quality NTEBs and differentiation into cardiomyocytes more efficiently in vitro.

Expression localization of Bmi1 in mice testis.

B cell-specific Moloney murine leukaemia virus integration site 1 (Bmi1), known as the first functional member of PcG (Polycomb Group) family, is supposed to be a key regulator of stem cell self-proliferation. In this study, we investigated its expression in testis and its impact on spermatogonia proliferation for better understanding of its role in spermatogenesis. Results showed that Bmi1 was expressed in undifferentiated spermatogonia (A(s), A(pr) and A(al) spermatogonia). Overexpression of BMI1 could promote spermatogonia proliferation, while repression of endogenous Bmi1 by RNAi resulted in inhibition of the proliferation.

[Cloning of gdnf in the mouse testis and its expression in sertoli cells].

OBJECTIVE: To clone the glial cell line-derived neurotrophic factor (GDNF) from the mouse testis, construct the eukaryotic expression vector and transfect this vector into Sertoli cells in order to use the gdnf-transfected Sertoli cells as the feeder layer to cultivate spermatogonial stem cells (SSCs). METHODS: Total RNA was extracted from the testes of normal mature mice and gdnf was cloned and amplified using RT-PCR, inserted into the eukaryotic expression vector and transfected into sertoli cells (TM4 cell line). Immunofluorescence with anti-GDNF antibodies was performed at 40 h following the transfection. RESULTS: gdnf cDNA was cloned successfully, and GDNF expressed after transfected into Sertoli cells. CONCLUSION: This study provides a basis for culturing SSCs with gdnf-transfected Sertoli cells as the feeder layer.

[Infectious bovine rhinotracheitis viral gG expression and gG-ELISA development].

Taking the genome DNA of Infectious Bovine Rhinotracheitis Virus (IBRV) as the template, the gG gene was amplified with PCR and cloned into the T cloning vector pMD18-T. After being identified by restriction digestion and DNA sequencing, the insert was subcloned into the expression vector pGEX-KG. Sodium docecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Western blot assay showed that this gene was expressed as both soluble form and inclusion body by the transformed E. coli BL21 strain (DE3). The fusion protein was purified and used as the coating antigen to develop the indirect Enzyme-Linked Immunosorbent Assay (ELISA). Comparison between this gG-ELISA and commercial IBRV gB-ELISA Kit (IDEXX) was made in the detection of 380 cow serum samples. The results demonstrated an agreement of 92%. By using this novel gG-ELISA, 1248 cow serum samples were tested and the average positive rate of IBRV antibodies for imported cows is 21.7%, while the positive rate ranged greatly from 0.0%-41.5% for Hubei local Chinese Black and White Dairy Cows.

17beta-estradiol stimulates proliferation of spermatogonia in experimental cryptorchid mice.

AIM: To investigate whether estrogen stimulates the proliferation of spermatogonia or induces spermatogenesis in cryptorchid mice. METHODS: Mice were surgically rendered cryptorchid, then treated with different doses of 17beta-estradiol (E2) s.c. once a day. Mice were killed at sexual maturity (45 days of age), and histological analysis and immunofluorescence were performed. Serum follicle stimulating hormone (FSH), estradiol, testosterone and luteinizing hormone (LH) were measured. RESULTS: Low doses of E2 had no notable effect on spermatogonia, but at higher doses, E2 stimulated the proliferation of spermatogonia. CONCLUSION: E2 has a dose-related mitogenic effect on spermatogonia.

[Differential analysis of proteomic profiles between cryptorchid and normal mouse testes].

To screen factors related to spermatogonial stem cell (SSC) proliferation, and to investigate the mechanism of infertility caused by cryptorchidism, ten-day-old Kunming (KM) mice were used and experimental cryptorchidism was conducted. On the 35th day after cryptorchid operation, the left testes were fixed in Bouin's fluid and used for histological analysis. The testes of 45-day-old mice were subjected to the same histological analysis, and it was found that they contained germ cells at every stage of development, from SSCs to sperm, indicating that the animals were fully sexually mature at this age. While in experimental cryptorchid mice, the spermatogenesis was arrested at the stage of spermatocytes, and only spermatogonia and primary spermatocytes were present in cryptorchid testes. The proportion of spermatogonia to other types of germ cells was much higher than that in sexually mature mice. On the other hand, the right testes were used for proteomic analysis. The total protein in testes was extracted on the 35th day after cryptorchid operation. The differentially expressed proteins in cryptorchid mice and sexually mature mice were screened and compared by the proteomic techniques. Through the separation of two-dimensional gel electrophoresis (2-DE), 20 differential protein spots were found, and 9 of them were digested and identified by the matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) mass spectrum. In cryptorchid mice, 6 out of 9 proteins were down-regulated, and 3 were up-regulated. Among these proteins, 4 proteins were identified, and they were Stathmin, phosphatidylethanolamine-binding protein1 (PEBP1), HES-related basic helix-loop-helix protein (HERP), and one unnamed protein (we temporarily named it Px). More Stathmin, PEBP1 and Px were expressed in sexually mature mice than in experimental cryptorchid mice. But HERP1 was the other way round. In the present study, we have screened 4 proteins related to cryptorchidism. It is helpful to study the mechanism of SSC proliferation and infertility caused by cryptorchidism.

[Cloning of Bmi1 cDNA from mouse testis and its expression in E. coli BL21].

OBJECTIVE: To produce BMI1 polyclonal antibody, mouse Bmi1 cDNA was cloned from mouse testis and expressed in E. coli BL21. METHODS: Bmi1 gene was amplified from mouse testis by RT-PCR and inserted into the prokaryotic expression vector pET-28c(+). Subsequently the recombined vector was transformed and expressed in E. coli BL21 (DE3) and the immunogenicity of recombined protein BMI1 (rBMI1) was tested by Western blot. RESULTS: Mouse Bmi1 cDNA of 975 bp was successfully cloned and recombined. E. coli BL21 strains expressed rBMI1 were screened. The expression protein amounted to 12% of the total bacterial protein after induced with IPTG, which included inclusion body and soluble protein. Inclusion body was the major pattern of the expression that amounted to 71% of the insoluble protein. Western blot analysis showed that rBMI1 could be specially recognized by mouse monoclonal IgG1 anti-BMI1 and His-tag antibody. CONCLUSION: There was expression of Bmi1 gene in mouse testis. Mouse Bmi1 cDNA was successfully cloned and expressed prokaryoticly.

Construction of a unidirectionally beating 3-dimensional cardiac muscle construct.

BACKGROUND: Cardiac tissue engineering aims to construct cardiac tissue with characteristics similar to those of the native tissue. Engineered cardiac tissues (ECTs) can be constructed using synthetic scaffold or liquid collagen. We report an initial study using our own newly designed cardiac muscle device to construct heart tissue. We investigated the effects of cell seeding density and collagen quantity on the formation of liquid collagen-based cardiac muscle. METHODS: We obtained cardiac myocytes from neonatal rats mixed with collagen type I and matrix factors cast in circular molds to form circular strands. Cell densities (0.1 x 10(7) to 6 x 10(7)) and collagen quantity (0.3 to 1.0 ml/ECT) were tested. Cell gross morphology, cell orientation, spatial distribution and ultrastructure were evaluated using histologic analyses, confocal laser scanning microscopy and transmission electron microscopy. RESULTS: Histologic analyses of ECTs revealed that cardiac cells reconstituted longitudinally oriented, cardiac bundles with morphologic features characteristic of the native tissue. Confocal and electron microscopy demonstrated that, using optimized cell density and collagen quantity, we made ECTs with characteristic features similar to those of native differentiated myocardium. CONCLUSIONS: ECTs comparable to native cardiac tissue can be engineered under optimized conditions. This construct is a first step in the development of cardiac tissue engineered in vitro, and may be used as a basis for studies of cardiac development, drug testing and tissue replacement therapy.