Engineering calcium deposits on polycaprolactone scaffolds for intravascular applications using primary human osteoblasts

A novel combination of nano-scaffolds with micro-scaffolds to mimic extracellularmatrices improve osteogenesis

To improve bone engineering for clinical applications, we coupled nanofiber-peptide hydrogel to nano-hydroxyapatite/collagen to form a bioactive scaffold (cnHAC) that mimics extracellular matrices. In comparison to nano-hydroxyapatite/collagen, we found that cnHAC promoted cell adhesion and spreading, and DNA content measurements, alkaline phosphatase activity assays, and reverse transcriptase-polymerase chain reaction analyses of osteogenic gene expression showed that cnHAC significantly improved cellular attachment, proliferation, and osteogenic differentiation in vitro ( P < 0.05). In vivo models based on rat calvarial implants showed that cnHAC significantly enhanced bone regeneration ( P < 0.05). In conclusion, we demonstrated that novel cnHAC scaffolds could potentially facilitate future bone regenerative medicine.

In vitro cytotoxicity and in vivo osseointergration properties of compression-molded HDPE-HA-Al2O3 hybrid biocomposites

The aim of this study was to investigate the in vivo biocompatibility in terms of healing of long segmental bone defect in rabbit model as well as in vitro cytotoxicity of eluates of compression-molded High density polyethylene (HDPE)-hydroxyapatite (HA)-aluminum oxide (Al2O3) composite-based implant material. Based on the physical property in terms of modulus and strength properties, as reported in our recent publication, HDPE-40 wt % HA and HDPE-20 wt % HA-20 wt % Al2O3 hybrid composites were used for biocompatibility assessment. Osteoblasts cells were cultured in conditioned media, which contains varying amount of composite eluate (0.01, 0.1, and 1.0 wt %). In vitro, the eluates did not exhibit any significant negative impact on proliferation, mineralization or on morphology of human osteoblast cells. In vivo, the histological assessment revealed neobone formation at the bone/implant interface, characterized by the presence of osteoid and osteoblasts. The observation of osteoclastic activity indicates the process of bone remodeling. No inflammation to any noticeable extent was observed at the implantation site. Overall, the combination of in vitro and in vivo results are suggestive of potential biomedical application of compression-molded HDPE- 20 wt % HA- 20 wt % Al2O3 composites to heal long segmental bone defects without causing any toxicity of bone cells.

Poly-є-caprolactone based formulations for drug delivery and tissue engineering: A review

Biodegradable polymer based novel drug delivery systems have provided many avenues to improve therapeutic efficacy and pharmacokinetic parameters of medicinal entities. Among synthetic biodegradable polymer, poly-є-caprolactone (PCL) is a polymer with very low glass transition temperature and melting point. Owing to its amicable nature and tailorable properties it has been trialed in almost all novel drug delivery systems and tissue engineering application in use/investigated so far. This review aims to provide an up to date of drugs incorporated in different PCL based formulations, their purpose and brief outcomes. Demonstrated PCL formulations with or without drugs, intended for drug delivery and/or tissue engineering application such as microsphere, nanoparticles, scaffolds, films, fibers, micelles etc. are categorized based on method of preparation.

Calcification of primary human osteoblast cultures under flow conditions using polycaprolactone scaffolds for intravascular applications

Total atherosclerotic occlusion is a leading cause of death. Recent animal models of this disease are devoid of cell-mediated calcification and arteries are often not occluded gradually. This study is part of a project with the objective of developing a new model featuring the above two characteristics, using a tissue-engineering scaffold. The amount and distribution of calcium deposits in primary human osteoblast (HOB) cultures on polycaprolactone (PCL) scaffolds under flow conditions were investigated. HOBs were cultured on PCL scaffolds with TGF-β1 loadings of 0 (control), 5 and 50 ng. HOB-PCL constructs were cultured in spinner flasks. Under flow conditions, cell numbers present in HOB cultures on PCL scaffolds increased from day 7 to day 14, and most calcification was induced at day 21. TGF-β1 loadings of 5 and 50 ng did not show a significant difference in ALP activity, cell numbers and amount of calcium deposited in HOB cultures, but calcium staining showed that 50 ng TGF-β1 had higher calcium deposited on both days 21 and 28 under flow conditions compared with 5 ng of loading. Amount of calcium deposited by HOBs on day 28 showed a decrease from their levels on day 21. PCL degradation may be a factor contributing to this loss. The results indicate that cell-induced calcification can be achieved on PCL scaffolds under flow conditions. In conclusion, TGFβ1-HOB loaded PCL can be applied to create a model for total atherosclerotic occlusion with cell-deposited calcium in animal arteries.