Mechanical and histological properties of an electrospun scaffold with a modified surface by plasma polymerization implanted in an in vivo model

This article presents the construction of scaffolds composed of polylactic acid(PLA)with different concentrations of hydroxyapatite(HA)by electrospinning,which were superficially modified with polypyrrole(PPy/I)by plasma polymerization.A preliminary study was conducted of the biological and mechanical behavior of the scaffolds when they were implanted in the back of rabbits for 30 days;bone cells differentiated from mesenchymal stem cells(MSCs)were used.The bone cell and scaffold structures were characterized by histological,immunohistochemical,and mechanical stress tests.Hematoxylin–eosin staining showed good tissue conformation.The immunohistochemical tests highlighted the presence of the main bone tissue proteins,such as collagen,osteocalcin,and osteopontin.The PLA/HA scaffolds were observed to exhibit cell adhesion and proliferation properties;however,the response was much better in the scaffolds that had a higher concentration of HA and that were coated with PPy/I.The results of the mechanical tests of the scaffolds indicated that the plasma treatment improved the adhesion and cell proliferation properties and contributed to the mechanical support,allowing the formation of neotissues with good viability of cell growth.

Hepatocyte culture in a radial-flow bioreactor with plasma polypyrrole coated scaffolds

We have designed and evaluated a radial-flow bioreactor for three-dimensional liver carcinoma cell culture on a new porous coated scaffold.We designed a culture chamber where a radial flow of culture medi-um was continuously delivered through it.Once this system was established,flow was simulated using flow dy-namics software based on numeric methods to solve Navier-Stockes flow equations.Perfusion within cell culture scaffolds was simulated using a flow velocity of 7 mL/min and found that cell culture medium was distributed unhindered in the bioreactor chamber.Afterwards,the bioreactor was built according to the simulated design and was tested with liver carcinoma cells(HepG2)cultured over an L-polylactic acid scaffold whose surface was modified with iodine-doped polypyrrole.The bioreactor was tested under non-flow and in radial flow condi-tions.Cell density under radial flow conditions was almost double than that under static conditions and both total protein and albumin output was also increased under radial flow conditions.

Effect of synthesis variables of plasma synthesized polymers on growth of HepG2 cells

Low pressure plasma polymer films were synthesized using pyrrole and allylamine monomers and adding iodine was used(or not)for the reaction in both cases.They were polymerized on glass substrates under the same reaction conditions.Polymerization of allylamine was also studied at different operating powers.These thin polymer films were used as culture surfaces for HepG2 cells,a cell line derived from a human hepatoma.The proliferation,differentiation and two-dimensional propagation until obtaining monolayer of the cells was studied on the different synthetized films and correlations were established between the conditions of synthesis,the physicochemical characteristics obtained and the performance as substrates for the cellular growth.