Interaction studies of mixed matrices of chitosanpoly-ε-caprolactone and alendronate for bone tissue engineering

Abstract

Tissue engineering actual tendencies leads to the development of biocompatible matrices with accurate physical and mechanical properties in bone reconstruction. As a regeneration of a new tissue is achieved, the scaffold is no longer needed and so it is reasonable to use biodegradable scaffolds. The rate of degradation must be in parallel with the tissue regeneration, and is very important to provide long term construct biocompatibility, because only natural tissue will remain in the body–a neo-organ. In this context one of the most common compound used is the natural polymer chitosan, whose mechanical properties can be improved by adding synthetic polymers. The great interest in this macromolecule is due to its proved biocompatibility and biodegradation properties. Matrix also requires the capacity to transport osteogenic agents which enhance bone regeneration. Bisphosphonates are a new class of synthetic compounds structurally related to pyrophosphate, an endogenous modulator in homeostasis of calcium, and they are clinically used for various metabolic bone disorders such as Paget’s disease, hypercalcemia of malignancy, bone metastasis and osteoporosis. The reduced targetability of some bisphosphonates in relationship to the dose increased and its hepatosplenic accumulation has been reported. It is due to high precipitability with divalent ions in the circulation in blood plasma, which may be taken up by reticuloendothelial system as foreign substances. Therefore, new drug delivery systems are needed to overcome these problems. The aim of our work is the development of a scaffold for tissue engineering based in chitosan/poly-ε-caprolactone blend which contains an adequate concentration of alendronate (a nitrogen bisphosphonate) for osteoblastic bone growth without toxic effects.