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

Abstract

Because of the three-dimensional structure of bone or hard tissue such as a tooth, a scaffold is necessary for its regeneration by cellular engineering. Commonly, for in vivo examination, hydroxyapatite (HA) has been used as such a scaffold. Cylindrical HA with a hollow center, which included a columnar formalin-treated polyvinyl alcohol sponge, was used in this examination as a scaffold. The sponge had been coated with L-tryptophan or L-lysine before insertion into the hollow center of the HA. Rat bone marrow cells (rBMCs) derived from the femur were seeded in the sponge before insertion into the hollow center of HA. The number of rBMCs seeded in each sponge was 1.5 × 10 6 . These scaffolds were implanted subcutaneously into the backs of Fischer 344 rats for 6 weeks. In the amino-acid-coated sponge in HA, osteogenesis was found histologically. An osteocalcin level of approximately 10 µg was measured in the scaffolds with L-tryptophan-coated formalized polyvinyl alcohol sponge containing rBMCs, 4 µg on average in the scaffolds with L-lysine-coated sponge containing the cells and about 2 µg in each scaffold with uncoated sponge containing the cells. The structure of the scaffolds used in this study was thought to be suitable for osteogenesis by rBMCs. It was concluded that tryptophan, as a factor for bone formation by stem cells, functioned by promoting cell adhesion and the differentiation of stem cells into osteoblasts.

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

“…In the bi-phasic scaffolds in this study, bone was formed conspicuously in the sponge The histological examination of the formaldehyde-acetalized PVF sponge implanted in subcutaneous tissue demonstrated that this sponge is superior in terms of biocompatibility. However, the PVF sponges are non-biodegradable, as previously reported [13] [19] [20]. These sponges were developed 60 years ago and used as a filling material for soft defects [21].…”

“…However, it was reported that if the sponge was used as the scaffold, adhesion to the fine construction of the material would be difficult for stem cells [12]. Thus, in a previous study, to improve the cell adhesion properties, a PVF sponge was coated with tryptophan or lysine in the bi-phasic scaffold and in vivo osteogenesis was measured with rat bone marrow cells [13]. A high level of osteogenesis in the sponge of the bi-phasic scaffold was observed.…”

Influence of Hydroxyapatite Surface Functionalization on Thermal and Biological Properties of Poly(l-Lactide)- and Poly(l-Lactide-co-Glycolide)-Based Composites

“…In place of such commonly used reagents, l- lysine was proposed to assist PEG grafting and to improve osteological bioactivity of the composites. l- lysine is known to promote the adhesion of osteoblasts to the surface of the material, which may positively correlate with cell proliferation [ 10 , 11 ], and was found to improve the osteogenic potential of the bone marrow stromal cells [ 12 ]. l- lysine can be used as a food supplement and its intake benefits in increased bone mineral density and lowered prevalence of osteoporosis [ 13 ].…”