Effects of the injectable glycol-chitosan based hydrogel on the proliferation and differentiation of human dental pulp cells / 北京大学学报(医学版)

OBJECTIVE@#To prepare glycol-chitosan (GC)-based single/dual-network hydrogels with different composition ratios (GC31, DN3131 and DN6262) and to investigate the effects of hydrogel scaffolds on biological behavior of human dental pulp cell (hDPC) encapsulated.@*METHODS@#GC-based single-network hydrogels (GC31) and GC-based dual-network hydrogels (DN3131, DN6262) with different composition ratios were prepared. The injectability was defined as the average time needed to expel a certain volume of hydrogel under a constant force. The degradation of the hydrogel was determined by the weight loss with time. The fracture stress was measured using a universal testing machine. The proliferation of hDPCs in hydrogels was detected using the cell counting kit-8 (CCK-8) method and CalceinAM/PI Live/Dead assay. After 14 days of odontoblastic induction, the expression of alkaline phosphatase (ALP), dentin sialophosphoprotein (DSPP) and dentin matrix protein-1 (DMP-1) was detected by real-time quantitative reverse transcription PCR (real-time RT-PCR) and the mineralized nodules was observed by Von Kossa staining.@*RESULTS@#The injectability of all three groups of hydrogels was acceptable. The time of injection of GC31 was the shortest, and that of DN6262 was longer than DN3131 (P<0.05). The degradation rate of GC31 hydrogel in vitro was significantly faster than that of the dual-network hydrogel groups (P<0.05). There was no significant difference between DN3131 and DN6262 (P>0.05). The compressive resistance failure point of GC31 group was 1.10 kPa, while it was 7.33 kPa and 43.30 kPa for DN3131 and DN6262. The compressive strength of dual-network hydrogel was significantly enhanced compared with single-network hydrogel. hDPCs were in continuous proliferation in all the three groups, and the GC31 group showed a higher proliferation rate (P<0.05). The expression levels of DSPP, DMP-1 and ALP in the dual-network hydrogel groups (DN3131, DN6262) were significantly higher than that of GC31 after culturing for 14 days (P<0.05), there was no difference in the expression levels of DMP-1 and ALP between DN3131 and DN6262 (P>0.05); Von Kossa staining showed that more mineralization deposition and mass-shaped mineralized nodules formed in DN3131 and DN6262, while only light brown calcium deposition staining was observed in GC31 group, which was scattered in granular forms.@*CONCLUSION@#GC-based single/dual network hydrogels with different composition ratios met the injectable requirements. GC31 group had a lower mechanical properties, in which hDPCs exhibited a higher proliferation rate. dual-network hydrogels had slower degradation rate and higher mechanical properties, in which hDPCs exhibited better odontoblastic differentiation potential and mineralization potential.

Synthesis and experimental study of a novel polymer/gene compound drug controlled release system for the treatment of erectile dysfunction / 中华男科学杂志

<p><b>OBJECTIVE</b>To overcome the deficiency in the current therapies for erectile dysfunction (ED), we designed and synthesized a novel high-efficiency polymer/gene compound drug controlled release system and discussed the feasibility of pH and temperature dually sensitive injectable hydrogel in ED gene therapy.</p><p><b>METHODS</b>We synthesized optimal siRNA gene nanoparticles by characterizing the zeta potential of polylysine (PLL)/siRNA gene compounds, and established a pH and temperature dually sensitive injectable gene compound drug controlled release system via Schiffs reaction between glycol chitosan (GC) and benzaldehyde capped OHC-PEO-PPO-PEO-CHO. Then we demonstrated the sustained release of the system at different temperatures.</p><p><b>RESULTS</b>When the mass ratio of PLL to siRNA was 20:1, the zeta potential of the PLL/siRNA gene compound reached the peak (+23.5 mV) and the siRNA was encapsulated by PLL in the maximal degree. GC and OHC-PEO-PPO-PEO-CHO was crosslinked via benzoicimine reaction when environmental pH was changed from 5.5 to 7.4. The reslease of the siRNA encapsulated in this system kept at a low rate at 37 degrees C, significantly enhanced with the increase of the temperature to 60 degrees C, rising to (122.5 +/- 5.3) microg at 1 000 minutes as compared with (23.8 +/- 6.0) microg at 37 degrees C (P < 0.05).</p><p><b>CONCLUSION</b>The polymer/gene compound drug controlled release system was successfully synthesized, which improved the stability and capacity of gene carriers and achieved siRNA release at different temperatures, promising to be a new approach to the gene therapy of ED.</p>