[Research progress in ectopic grafting of testicular tissues].

Since Nature published the first report in 2002 on using immunodeficient mice as recipients and allogeneous or heterogeneous testes as donor tissues to study the ectopic development of spermatogenic cells, the technique has been widely applied in various species (including human). In comparison with other in vitro maturation methods for male germ cells, testicular allografting or xenografting technique has such advantages as similar environment for the development of germ cells in physiological conditions, and better reproducibility. Up to now, sperm has been successfully produced by this technique from the testicular tisues of the immature mouse, hamster, cat, rabbit, pig, goat, bovine and rhesus monkey, and their offspring have even been generated by ICSI technique using the mouse and rabbit sperm derived from testis grafts. This article comprehensively reviews the development of the technique by discussing the influencing factors on the germ cell development in grafts including the variety and age of donors, the sex, integrity and immunity of recipients, the graft location and grafting time. And the applications of the technique and the existing problems are discussed as well.

[A study on HLA-DQB1 allele associated with genetic susceptibility to duodenal ulcer in Guangdong Hans].

OBJECTIVE: To study the genetic susceptibility of HLA-DQB1 alleles to duodenal ulcer in Chinese Hans from Guangdong area around. METHODS: Hundred and five patients with duodenal ulcer and hundred and five healthy controls were examined for HLA-DQB1 genotypes. HLA-DQB1 allele typing was carried out by polymerase chain reaction with sequence specific primers (PCR-SSP). RESULTS: The allele frequency of HLA-DQB1*0602 in patients with duodenal ulcer (64.8%) was significantly higher than that in healthy controls (14.3%). CONCLUSION: These findings suggest that HLA-DQB1*0602 is a susceptible gene to duodenal ulcer in Guangdong Hans of China. And at HLA-DQB1 site, there are immunogenetic differences between duodenal ulcer patients and healthy controls.

Development of neonatal mouse and fetal human testicular tissue as ectopic grafts in immunodeficient mice.

AIM: To investigate the stepwise development and germ cell gene expression in allografted neonatal mouse testes and the differentiation of immature human testicular cells in xenografted human testes. METHODS: Immunodeficient nude mice were used as hosts for allografting of neonatal mouse testes and xenografting of human fetal testicular tissues. Stepwise development and stage-specific gene expression of germ cells in allografts were systematically evaluated and parallel compared with those in intact mice by periodically monitoring the graft status with measurement of graft weight, histological analysis and determination of five stage-specific genes. Human testicular tissues from 20 and 26 weeks fetuses were used for the xenografting study. Histological analysis of xenografts was performed 116 and 135 d after the grafting procedure. RESULTS: In the allografting study, progressive increase in tissue volume and weight as well as in tubule diameter in grafts was observed; the appearance time of various germ cells in seminiferous tubules, including spermatogonia, spermatocytes, round and elongate spermatids and sperm, was comparable with that in intact donors; the initiation of gene transcription in grafts showed a similar trend as in normal mice. Graft weight ceased to increase after 7-8 weeks and degradation of grafts was observed after 5 weeks with progressive damage to seminiferous epithelium. In the xenografting study using immature human testicular tissues, graft survival and development was indicated by increasing graft weight, Sertoli cells differentiation into advanced stage, germ cells migration and location to the basal lamina and formation of a niche-like structure. CONCLUSION: The developmental course and gene expression pattern of germ cells in allografts were similar to those in intact mice. The best time point for retrieval of mouse sperm from grafts was 5-7 weeks after grafting procedure. An accelerated development of immature human testicular cells could be achieved by ectopic xenografting of human testes.

[Conversion of human umbilical cord blood-derived cells into hepatocyte-like cells in a culture system mimicking hepatic injury].

OBJECTIVE: To explore the effect of the microenvironment induced by damaged mouse hepatic cells on the conversion of human umbilical cord blood-derived cells into hepatocyte-like cells. METHODS: A hepatic injury-like microenvironment was mimicked using carbon tetrachloride damaged mouse hepatic cells, where mononuclear cells (MNC) from human umbilical cord blood were cultured in a compartment separated by trans-well membrane. Histochemical staining, reversed transcription-polymerase chain reaction (RT-PCR) and gene sequencing were performed for the information on the conversion of human umbilical cord blood MNC. RESULTS: A number of PAS positive stained cells in MNC co-cultured with damaged mouse hepatic cells were observed after 72 h. Cells expressing mature hepatocyte markers, human albumin (hALB) and human GATA-4 (hGATA-4) mRNA were detected by RT-PCR, which was further confirmed with sequencing. Relevant control groups, MNC co-cultured with normal mouse hepatic cells and MNC cultured alone remained negative. CONCLUSION: The culture system using damaged mouse hepatic cells as stimulator could be a potential in vitro system for the conversion of human umbilical cord blood-derived cells into hepatocyte-like cells.

[Establishment of animal model for in vitro spermatogenesis by heterotopic grafting of neonatal mouse testis].

OBJECTIVE: To establish an in vitro model for the development of mouse spermatogenic cells into sperm by using the immunodefective mouse as the incubator. METHODS: Tissue grafting was performed using testis from 1-2 days old Kun-ming mice as donor tissue and immunodefective mice as recipients; the expression of TESK1 mRNA in grafts was determined by RT-PCR and the spermatogenesis further observed with histological analysis of grafts. RESULTS: Molecular biological and histological analyses showed that grafts post-grafting not only expressed TESK1 mRNA as in normal mouse testis, but also exhibited similarities in the structure of seminiferous tubules and component of spermatogenic cells, including sperms. CONCLUSION: Spermatogenic cells heterotopically grafted in vitro could continuously grow and complete spermatogenesis and finally develop into sperm.