Development of castor polyurethane scaffold (Ricinus communis L.) and its effect with stem cells for bone repair in an osteoporosis model

Abstract

The development of ‘smart’ scaffolds has achieved notoriety among current prospects for bone repair, especially for chronic osteopathy, such as osteoporosis. Millions of individuals in the world suffer from poor bone healing due to osteoporosis. The objective of this work was to produce and characterize castor polyurethane (PU) scaffolds (Ricinus communis L.) and evaluate its in vitro biocompatibility with stem cells and osteoinductive effect in vivo on bone failures in a leporid model of osteoporosis. The material was characterized using Fourier-transform infrared spectroscopy, thermogravimetric analysis, SEM, and porosity analysis. Then, the biocompatibility was assessed by adhesion using SEM and cytotoxicity in a 3-(4, 5-dimethyl-2-thiazolyl)-2, 5-diphenyl-2H-tetrazolium assay. The osteoinductive effect in vivo was determined in bone defects in rabbit tibias (Oryctolagus cuniculus) submitted to castor PU scaffold, castor PU scaffold associated with stem cells, and negative control, after four and eight weeks, evaluated by computed microtomography and histopathology. The scaffolds were porous, with an average pore size of 209.5 ± 98.2 µm, absence of cytotoxicity, and positive cell adhesiveness in vitro. All the animals presented osteoporosis, characterized by multifocal osteoblastic inactivity and areas of mild fibrosis. There were no statistical differences between these treatments in the fourth week of treatment. In the eighth week, the treatment with castor PU scaffold alone induced more significant bone formation when compared to the other groups, followed by treatment with an association between castor PU scaffold and stem cells. The castor PU scaffold was harmless to cell culture, favoring cell adhesiveness and proliferation, in addition to inducing bone neoformation in osteoporotic rabbits.

Scaffold based on castor oil as an osteoconductive matrix in bone repair: biocompatibility analysis

“…The spectra obtained by Fourirer transform infrared spectroscopy were compatible with what has already been reported in the literature, confirming the standardization of the scaffolds production. In the thermal analysis, the biomaterial also behaved in a predicted way, showing thermal degradation in three different stages, starting at 180ºC, going through 280ºC and ending at 380ºC with the greatest loss of mass (57%), according to previous studies [7][8][9] .…”

“…The scaffolds were found from castor oil monoglyceride and characterized as described in previous studies [7][8][9] . The pure Castor oil was commercially acquired.…”

“…Hexamethylene diisocyanate (HDI) was added at a ratio of 1:4.5 (MAG:HDI), still under composition until completion of polymerization. During the temperature, it was possible to observe the formation of the spongy material, remaining 12 hours at the initial temperature until the end of the process [7,8] .…”

“…To confirm the presence of the materials in the sample, spectroscopy was performed in a Thermo Fisher Scientific Nicolet iS5 apparatus, with a purge pump and a wavelength between 800 cm -1 and 4000 cm -1 , 128 accumulated cans, 4 cm -1 resolution, in attenuated total reflection. To verify the stability and thermal decomposition as a function of mass loss, the thermal analyzer TGA-51H, Shimadzu, standardized with a heating rate of 10 •C min -1 in a nitrogen atmosphere, up to a temperature of 600 •C and a sample mass of approximately 7 mg [7][8][9] .…”

Surface and micromechanical analysis of polyurethane plates with hydroxyapatite for bone structure

“…SEM images are threedimensional and suitable for analyzing and evaluating the surface area of polymer samples [23] . This tool investigates the fracture zone and tries correlating the topographical features of the sample surface [24,25] . Thus, the resulting photomicrographs characterized the surface topography aspects of castor oil-based PU with HA.…”