Hybrid Scaffolds Composed of Amino-Acid Coated Sponge and Hydroxyapatite for Hard Tissue Formation by Bone Marrow Cells

Abstract

A formalin-treated polyvinyl-alcohol (PVF) sponge is convenient as a scaffold because its configuration is easily modified. However, coating the sponge with an adhesive chemical agent is necessary to attach bone marrow cells (BMCs) to the sponge structure. Moreover, it was considered that a hybrid scaffold composed of a sponge and enveloped cylindrical porous hydroxyapatite (HA) would be convenient. In this study, the effect of leucine (Leu) coating on a PVF sponge was examined for osteogenesis on an HA/PVF hybrid scaffold by rat BMCs (rBMCs). In an in vivo assessment, the sponge immersed in Leu solution (10 mg/ml) was inserted into the hollow center of cylindrical HA. The sponge received 1.5 × 10 6 rBMCs obtained from male Fischer 344 rats. The hybrid scaffolds were then implanted subcutaneously of syngeneic rats for 6 weeks. In vitro assessment of Leu to hard tissue formation with coating on the well or addition in rBMC culture medium was also performed in a 6-well plate for 2 weeks. In vivo examinations showed the excellent effect of Leu coating on PVF sponge. Leu-coated PVF sponge in the scaffolds showed marked new bone formation in the pores by histological examination. Leu-coated PVF sponge showed a high quantity of osteocalcine (OC). HA might prevent the release of rBMCs from PVF as a barrier. In in vitro examinations, the quantity of OC in rBMC culture with and without the addition of Leu in culture medium showed no significant difference. However, addition of Leu showed significant ALP activity level in culture medium. Leu coating in culture plate wells showed no influence on the quantity of OC. It was concluded from the results that Leu might prevent the emigration of rBMCs to the outside of the scaffold and promote the differentiation of cells to osteoblasts in the scaffold.

<i>In Vivo</i> Estimation of Osteogenesis by Bone Marrow Cells in a Bi-Phasic Scaffold and in Each of Its Components

“…However, bone was formed in the PVF sponge by rBMCs in the bi-phasic scaffold. A bi-phasic scaffold consisting of a cylindrical porous HA and PVF sponge was demonstrated as superior to a cylindrical porous HA scaffold that was previously used for the induction of bone[25]. The effects on bone formation of the bi-phasic scaffold were confirmed inthe rMBC-seeded PVF sponge.…”

Bone Formation in a Scaffold Composed of Cylindrical Hydroxyapatite and Tryptophan- or Lysine-Coated Sponge <i>in Vivo</i>

“…In addition, it was also found that the amino acids might support the promotion of bone formation in a scaffold. It was mentioned previously that bone formation in PVF was difficult because rBMCs did not adhere to the fiber structure of a PVF sponge [5] [23]. However, in this study, bone was clearly induced in the scaffold including a sponge coated with L-tryptophan or L-lysine in the cylindrical HA structure.…”

“…In this regard, attention was focused on the potentialities of some amino acids. Previously, the effectiveness of L-leucine for osteogenesis by its coating of a sponge component in a scaffold was reported [5]. In the present study, L-tryptophan and L-lysine were selected as factors for bone formation and their effects were evaluated.…”