Effects of hydroxyapatite and PDGF concentrations on osteoblast growth in a nanohydroxyapatite-polylactic acid composite for guided tissue regeneration

The technique of guided tissue regeneration (GTR) has evolved over recent years in an attempt to achieve periodontal tissue regeneration by the use of a barrier membrane. However, there are significant limitations in the currently available membranes and overall outcomes may be limited. A degradable composite material was investigated as a potential GTR membrane material. Polylactic acid (PLA) and nanohydroxyapatite (nHA) composite was analysed, its bioactive potential and suitability as a carrier system for growth factors were assessed. The effect of nHA concentrations and the addition of platelet derived growth factor (PDGF) on osteoblast proliferation and differentiation was investigated. The bioactivity was dependent on the nHA concentration in the films, with more apatite deposited on films containing higher nHA content. Osteoblasts proliferated well on samples containing low nHA content and differentiated on films with higher nHA content. The composite films were able to deliver PDGF and cell proliferation increased on samples that were pre absorbed with the growth factor. nHA–PLA composite films are able to deliver active PDGF. In addition the bioactivity and cell differentiation was higher on films containing more nHA. The use of a nHA–PLA composite material containing a high concentration of nHA may be a useful material for GTR membrane as it will not only act as a barrier, but may also be able to enhance bone regeneration by delivery of biologically active molecules

Thermally-activated shape memory effect on biodegradable nanocomposites based on PLA/PCL blend reinforced with hydroxyapatite

[EN] In this work, the effect of the addition of different amount of nanosized hydroxyapatite (nHA) on the shape memory behavior of blends based on poly (lactic acid) (PLA) and poly (epsilon-caprolactone) (PCL) has been studied. In particular PLA/PCL blend with 70 wt % PLA has been reinforced with 0.5, 1 and 3 wt % nHA. Moreover, the relationship between the morphology and the final properties of the nanocomposites has been investigated by field emission scanning electron microscopy, confocal Raman spectroscopy and atomic force microscopy. In particular, PeakForce has been used to study quantitative nanomechanical properties of the multifunctional materials leading to conclusion that nHA increase the phase separation between PLA and PCL as well as act as reinforcements for the PCL-rich phase of the nanocomposites. Furthermore, excellent thermally-activated shape memory response has been obtained for all the nanocomposites at 55 degrees C. Finally, the disintegration under composting conditions at laboratory scale level was studied in order to confirm the biodegradable character of these nanocomposites. Indeed, these materials are able to be used for biomedical issues as well as for packaging applications where both thermally-activated shape memory effect and biodegradability are requested.Authors thank the Spanish Ministry of Economy, Industry and Competitiveness, MINEICO, (MAT2017-88123-P) and the Regional Government of Madrid (S2013/MIT-2862) for the economic support. M.P.A. and L.P. acknowledge the Juan de la Cierva (FJCI-2014-20630) and Ramon y Cajal (RYC-2014-15595) contracts from the MINEICO, respectively. The authors also thanks CSIC for the I-Link project (I-Link1149).Peponi, L.; Sessini, V.; Arrieta, MP.; Navarro-Baena, I.; Sonseca Olalla, Á.; Dominici, F.; Giménez Torres, E.... (2018). Thermally-activated shape memory effect on biodegradable nanocomposites based on PLA/PCL blend reinforced with hydroxyapatite. Polymer Degradation and Stability. 151:36-51. https://doi.org/10.1016/j.polymdegradstab.2018.02.019S365115

Effects of intestinal ischemia-reperfusion on major conduit arteries

Intestinal ischemia-reperfusion (I-R) is a common and serious clinical condition associated with simultaneous remote organ dysfunction. The purpose of this study was to investigate the effects of intestinal I-R on the vasomotor functions of major conduit arteries. Anesthetized rabbits were randomly assigned to one of three groups: sham-operated controls (Group I), and one-hour intestinal ischemia with two-hour reperfusion (Group II) or four-hour reperfusion (Group III). The following mechanisms of vasomotor functions were studied in abdominal aorta, superior mesenteric, renal, pulmonary, and carotid arterial rings: (1) endothelial-dependent vasodilation response to acetylcholine, (2) endothelial-independent vasodilation response to nitroprusside, (3) beta-adrenergic vasodilation response to isoproterenol, and (4) phenylephrine-induced vasoconstriction. Intestinal injury was quantified using malondialdehyde (MDA) concentration and wet-to-dry intestine weight ratio. Intestinal I-R did not affect the maximal responsiveness or the sensitivity to acetylcholine, nitroprusside, and isoproterenol in all the vessels studied. The maximal contractile response to phenylephrine increased significantly in mesenteric artery in Group II, (227.1 +/- 15.1% vs 152.8 +/- 11.7% in controls) (p < 0.05). Intestinal MDA concentration, a marker of oxidant injury, increased from 39.87 +/- 9.41 nmol/g to 67.8 +/- 8.8 nmol/g in group II (p < 0.01), and to 94.8 +/- 7.56 nmol/g in Group III (p < 0.001). Wet-to-dry intestine weight ratio increased from 3.62 +/- 0.12 to 4.28 +/- 0.17 in Group II (p < 0.01), to 4.62 +/- 0.14 in Group III (p < 0.001). These data indicate that although the intestines of the animals subjected to intestinal I-R are seriously injured, the smooth muscle relaxation of major conduit arteries was not affected