[Roles of ten eleven translocation proteins family and 5-hydroxymethylcytosine in epigenetic regulation of stem cells and regenerative medicine]

The methylation of cytosine is one of the most fundamental epigenetic modifications in mammalian genomes, and is involved in multiple crucial processes including gene expression, cell differentiation, embryo development and oncogenesis. In the past, DNA methylation was thought to be an irreversible process, which could only be diluted passively through DNA replication. It is now becoming increa-singly obvious that DNA demethylation can be an active process and plays a crucial role in biological processes. Ten eleven translocation (TET) proteins are the key factors modulating DNA demethylation. This family contains three members: TET1, TET2 and TET3. Although three TET proteins have relatively conserved catalytic domains, their roles in organisms are not repeated, and their expression has significant cell/organ specificity. TET1 is mainly expressed in embryonic stem cells, TET2 is mainly expressed in hematopoietic system, and TET3 is widely expressed in cerebellum, cortex and hippocampus. This family catalyzes 5-methylcytosine to 5-hydroxymethylcytosine and other oxidative products, reactivates silenced-gene expression, in turn maintains stem cell pluripotency and regulates lineage specification. With the development of tissue engineering, organ transplantation, autologous tissue transplantation and artificial prosthesis have been widely used in clinical treatment, but these technologies have limitations. Regenerative medicine, which uses stem cells and stem cell related factors for treatment, may provide alternative therapeutic strategies for multiple diseases. Among all kinds of human stem cells, adipose-derived stem cells (ADSCs) are the most prospective stem cell lineage since they have no ethical issues and can be easily obtained with large quantities. To date, ADSCs have been shown to have strong proli-feration capacity, secrete numerous soluble factors and have multipotent differentiation ability. However, the underlying mechanism of the proliferation, secretion, acquired pluripotency, and lineage specific differentiation of ADSCs are still largely unknown. Some studies have explored the role of epigenetic regulation and TET protein in embryonic stem cells, but little is known about its role in ADSCs. By studying the roles of TET proteins and 5-hydroxymethylcytosine in ADSCs, we could provide new theoretical foundation for the clinical application of ADSCs and the stem cell-based therapy. In the future, combined with bioprinting technology, ADSCs may be used in tissue and organ regeneration, plastic surgery reconstruction and other broader fields.

[Silicification of silk fibroin and their application in bone tissue engineering]

In bone tissue engineering, fabrication of scaffold materials that are biodegradable with regenerative functions is one of the most important research fields. Silk fibroin exhibits many favorable characteristics used as scaffold materials. Among them, hybrid silk fibroin/inorganic composites prepared by biomimetic mineralization have better biocompatibility, biomechanical properties, and biodegradability. At the same time, the hybrid silk fibroin/inorganic materials have much better osteoinduction and conduction properties than silk fibroin. Here, the recent advances in the preparation of silk fibroin/silica hybrid materials by combination or biomimetic silicification are reviewed, and the future research prospects of silicification of silk fibroin are discussed.

[Application of robotic-assisted versus conventional laparoscopy in ureteral reimplantation with psoas hitch]

OBJECTIVE

To compare the efficacy of robotic-assisted laparoscopic and conventional laparoscopic ureteral reimplantation with psoas hitch.

METHODS

We retrospectively analyzed the data of 10 patients undergoing robotic-assisted laparoscopic ureteral reimplantation with psoas hitch and 6 undergoing conventional laparoscopic ureteral reimplantation between June, 2013 and December, 2014 in the General Hospital of PLA. The indications, surgical techniques and outcomes of the two procedures were compared.

RESULTS

All the patients completed the laparoscopic procedures without conversion to open surgery. Robotic-assisted and conventional laparoscopic procedures were comparable in terms of the mean operation time (165.50=52.57 vs 152.50=73.60 min), mean volume of blood loss (81.00=69.35 vs 46.67=31.41 mL), mean duration of catheter retention (6.75=1.74 vs 7.50=2.43 days), and mean postoperative hospital stay (7.10=2.08 vs 8.67=3.14 days). The patients were followed up for a mean of 13.5 months, during which none of the patients experienced anastomotic leak, vesicoureteral reflux or hydronephrosis.

CONCLUSION

There are no significant differences in surgical indications, surgical techniques or postoperative effect between robotic-assisted and conventional laparoscopic procedures of ureteral reimplantation with psoas hitch, but robotic-assisted laparoscopy can reduced the complexity in operation and increase the surgical precision in patients with a history of pelvic surgery, pelvic adhesion or secondary reimplantation.

[Comparison of laparoscopic pyelolithotomy and percutaneous nephrolithotomy for renal pelvic stones larger than 2.5 cm]

OBJECTIVE

To compare the safety, efficacy and complications of laparoscopic pyelolithotomy (LPL) and percutaneous nephrolithotomy (PCNL) for treatment of renal pelvic stones larger than 2.5 cm.

METHODS

From 2011 to 2016, 32 patients underwent LPL and another 32 patients received PCNL for renal pelvic stones larger than 2.5 cm. The baseline characteristics of the patients, stone size, mean operative time, estimated blood loss, postoperative hospital stay, stone-free rate, postoperative analgesia, blood transfusion, and the intraoperative, early postoperative and long-term complications were compared between the two groups.

RESULTS

The baseline characteristics and stone size were comparable between the two groups. The mean operative time of LPL and PCNL was 117∓23.12 and 118.16∓25.45 min, respectively (P>0.05). The two groups showed significant differences in the mean estimated blood loss (63∓11.25 vs 122∓27.78 mL, P<0.01) and blood transfusion rate (0 vs 6.2%, P<0.01) but not in postoperative hospital stay (4.5∓1.34 vs 4.8∓2.2 days, P>0.05), stone-free rate (93.1% vs 87.5%, P>0.05) or the postoperative analgesia time (1.7∓0.5 and 1.9∓0.6 days, P>0.05). The incidence of intraoperative complications were significant lower in LPL group than in PCNL group (6.2% vs 25.0%, P<0.01), but the incidences of early postoperative complications (25.0% vs 34.4%, P>0.05) and long-term postoperative complications (9.4% vs 12.5%, P>0.05) were similar between them.

CONCLUSION

PCNL is the standard treatment for pelvic stones larger than 2.5 cm, but for urologists experienced with laparoscopic technique, LPL provides a feasible and safe option for management of such cases.