BACKGROUND:Tissue-engineered bone scaffold fabricated by 3D-bioprinting technique has good controlability in morphology and structure. However, construction of tissue-engineered bone/cel growth factor complex and time-dose effect of sustained-release factors are needed to be further researched.
OBJECTIVE:To fabricate a sustained-release composite of polylactic-co-glycolic acid (PLGA)/nano-hydroxyapatite (n-HA) scaffold carrying bone morphogenetic protein-2 (BMP-2) using 3D-bioprinting technique, and test the biological properties of the PLGA/n-HA scaffold carrying BMP-2 and the sustained-release properties, thereby to discuss its feasibility as the tissue-engineered bone scaffold composite.
METHODS:Temperature-sensitive chitosan hydrogel was prepared using chitosan andβ-glycerophosphate to construct a sustained-release composite, chitosan nanoparticles carrying BMP-2 . 3D-bioprinting technique was utilized to fabricate the PLGA/n-HA scaffold carrying BMP-2. Biological features of the scaffold composite were tested, and time-dose effect of BMP-2 sustained-release was observed.
RESULTS AND CONCLUSION:The average pore size of the scaffold-cytokine composite was (431.31±18.40)μm, and the porosity was (73.64±1.82)%. The cumulative release rate of BMP-2 from the scaffold-cytokine composite that effectively controled the burst release during 48 hours and 30 days were suitable for the physiological needs. In conclusion, the porosity, pore size, release property, degradation rate, and mechanical strength of the scaffold-cytokine composite al meet the biological requirements of tissue-engineered bone construction.

Objective To compare the operative-postoperative outcomes of laparoscopic and robotassisted partial nephrectomy (LPN and RAPN) for patients with T1 b renal masses.Methods A total of 169 T1 b renal mass patients receiving LPN (n =69) or RAPN (n =100) in our center between October 2009 and October 2017 were retrospectively collected.There were 46 males and 23 females in LPN group,with a mean age of (55.0 ± 11.9) years.The mean tumor size was (5.09 ± 0.76) cm,and mean R.E.N.A.L score was 6.36 ± 1.53.49 procedures (71％) were performed via a retroperitoneal approach in LPN group.There were 59 males and 41 females in RAPN group with a mean age of (52.9 ± 11.7) years.The mean tumor size was(4.95 ±0.66) cm,and mean R.E.N.A.L score was 8.17 ± 1.50.31 procedures (31％)were performed via a retroperitoneal approach in RAPN group.There was statistical significance between two groups in R.E.N.A.L score and surgery approach (P ＜ 0.001).The group covariates were balanced through propensity score matching (PSM) using 1∶ 1 nearest neighbor matching method.After PSM,operating time,estimated blood loss,warm ischemia time,incidence of complications,hospital stay and postoperative follow-up status were compared between LPN(n =36)and RAPN(n =36)group.Results After PSM,patient distributions were closely balanced.In the LPN vs the RAPN group,there were significant different in warm ischemia time [(23.9 ± 7.3) min vs.(20.4 ± 6.7) min,P ＜ 0.05],estimated blood loss [(136.9 ± 80.2) ml vs.(136.9 ± 80.2) ml,P ＜ 0.05],incidence of complications (8.7％ vs.1.0％,P ＜0.05),and hospital stay [(11.5 ±3.8)d vs.(9.8 ± 1.80)d].There was no significant differences resulted regarding operating time [(164.5 ± 64.4) min vs.(169.0 ± 42.5) min,P ＞ 0.05],variation of estimated glomerular filtration rate from baseline [(9.97 ± 8.98)％ vs.(9.27 ± 9.19)％,P ＞ 0.05],positive surgical margin rate (1.4％ vs.0,P ＞ 0.05) and rate of recurrence or metastasis (1.4％ vs.1.4％,P ＞ 0.05) between groups.Conclusion Considering operative,functional and oncologic outcomes,both RAPN and LPN performed by an experienced surgeon were acceptable for patients with T1b renal masses.If available,robotic approach may reduce operative trauma and complications.