Design and biological evaluation of poly-lactic-co-glycolic acid (PLGA) mesh/collagen-chitosan hybrid scaffold (CCS) as a dermal substitute / 中华烧伤杂志

<p><b>OBJECTIVE</b>To design and construct a kind of dermal regeneration template with mesh, and to preliminarily evaluate its biological characteristics.</p><p><b>METHODS</b>PLGA mesh was integrated into CCS with freeze-drying method for constructing PLGA mesh/CCS composite (PCCS). The micromorphologies and mechanical properties among PLGA mesh, CCS, and PCCS were compared. PCCS and CCS was respectively implanted into subcutaneous tissue of SD rats (PCCS and CCS groups, 9 rats in each group). The tissue samples were collected at post operation week (POW) 1, 2, and 4 for histopathological and immunohistochemical observation. Protein levels of CD68, MPO, IL-1beta, IL-10 were examined by Western blot, with expression of gray value. Data were processed with one-way analysis of variance and t test.</p><p><b>RESULTS</b>Three-dimensional porous structure of PCCS was similar to that of CCS. Mechanical property of PLGA mesh and PCCS was respectively (3.07 +/- 0.10), (3.26 +/- 0.15) MPa, and they were higher than that of CCS [(0.42 +/- 0.21) MPa, F = 592.3, P < 0.0001)]. The scaffolds were filled with newly formed tissue in PCCS group at POW 2, while those in CCS group were observed at POW 4. A large accumulation of macrophages was observed in both groups, especially at POW 2, and more macrophage infiltration was observed in CCS group. The protein level of IL-10 in PCCS group at POW 2 was obviously higher than that in CCS group, while the protein levels of CD68, MPO, IL-1beta were significantly decreased as compared with those in CCS group (with t value from -4.06 to 2.89, P < 0.05 or P < 0.01).</p><p><b>CONCLUSIONS</b>PCCS has excellent mechanical property with appropriate three-dimensional porous structure. Meanwhile, it can rapidly induce formation of new tissue and vascularization, and it has a prospect of serving as a dermal substitute.</p>

Vascularization of poly-lactic-co-glycolic acid knitted mesh/collagen-chitosan hybrid scaffold / 中华烧伤杂志

<p><b>OBJECTIVE</b>To investigate the effects of poly-lactic-co-glycolic acid (PLGA) knitted mesh/collagen-chitosan hybrid scaffold (PCCS) on angiogenesis, and to explore the relative mechanisms.</p><p><b>METHODS</b>PLGA knitted mesh was integrated into collagen-chitosan scaffold (CCS) to construct PCCS with freeze-lyophilizing method, and CCS was made with the same method. The characteristics of morphology and water absorbing capacity among PCCS, PLGA knitted mesh, and CCS were compared in vitro. PCCS and CCS was respectively implanted into subcutaneous tissue of back on both sides in 24 SD rats, and the tissue specimens were harvested at post operation week (POW) 1, 2, and 4 according to the random number table to evaluate the level of angiogenesis by histopathological and immunohistochemical examinations. The expression levels of alpha smooth muscle actin (alpha-SMA) and vascular endothelial growth factor (VEGF) mRNA were examined by real-time quantitative RT-PCR. Data were processed with t test.</p><p><b>RESULTS</b>(1) PLGA knitted mesh was closely integrated with sponge of collagen-chitosan in PCCS, and the porous structure of PCCS was similar to that of CCS. (2) Compared with that of PCCS [(506 +/- 15)%], the water absorbing rate of CCS and PLGA knitted mesh was respectively increased and decreased [(627 +/- 21)%, (195 +/- 15)%, with t value respectively 3.8, 11.9, P < 0.05 or P < 0.001]. (3) The scaffolds were filled with newly formed tissue in CCS at POW 4, while those in PCCS were observed at POW 2 with more homogeneous and abundant collagen. (4) Blood vessels could be induced, and they grew into scaffolds along with prolongation of implantation time in PCCS and CCS. The number of mature blood vessels in PCCS at POW 1, 2, 4 [(10.7 +/- 3.2), (18.6 +/- 2.1), and (30.3 +/- 4.5) branches per square centimeter] was respectively higher than that in CCS [(5.4 +/- 0.9), (10.8 +/- 4.2), and (23.6 +/- 1.7) branches per square centimeter, with t value respectively 4.6, 4.4, 4.5, P values all below 0.01]. (5) The expression levels of alpha-SMA and VEGF mRNA in PCCS at POW 1, 2, 4 were significantly higher than those in the CCS (with t(alpha-SMA) value respectively 1.26, 1.63, 2.17, with t(VEGF) value respectively 5.52, 2.07, 1.78, P values all below 0.01).</p><p><b>CONCLUSIONS</b>PCCS is able to induce the ingrowth of blood vessels rapidly and promote their maturity. The mechanical properties and microstructures of scaffolds play synergistic role in the process of angiogenesis.</p>