Osteoconduction in keratin-hydroxyapatite composite bone-graft substitutes

Abstract

Reconstituted keratin-hydroxyapatite (K-HA) composites have shown potential as nonload-bearing bone graft substitute material. This in vivo study investigated the bone regeneration response of keratin plus 40% HA composite materials in comparison to collagen counterparts and an unfilled defect site. The implantation site was a noncritical size defect created in the long bones (tibia) of sheep, with observations made at 1, 2, 4, 6, 8, and 12 weeks postimplantation. Porous K-HA materials displayed an excellent biocompatibility similar to collagen counterparts; however, the rate of bone regeneration at K-HA implantation sites was markedly slower than that of the collagen or unfilled defect sites. While collagen materials were undetectable by 4 weeks implantation, K-HA composite remnants were present at 12 weeks. However, there is evidence that K-HA implants participated in the natural remodelling process of bone, with bone regeneration occurring via a creeping substitution mechanism. Observations imply that the rate of bone ingrowth into the K-HA defect site was matched with the rate of K-HA resorption. These results suggest that K-HA materials may offer significant benefits as nonload-bearing bone graft substitutes where it is desirable that the degradation of the scaffolding material be well matched with the rate of bone regeneration. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 2034-2044, 2017.

Amorphous calcium phosphate (ACP) in tissue repair process

“…This biphasic combination can be considered as ideal for bone regeneration, since HA improves the mechanical behavior of the material in addition to slower resorption, while β‐TCP acts in the early stages of biomaterial remodeling favoring the onset of bone deposition (MacMillan, Lamberti, Moulton, Geilich, & Webster, ). This process is also known as creeping substitution mechanism where a bone substitute is characterized by its functionality during degradation and as an osteoconductive substrate (Dias et al, ).…”

Wool‐derived keratin hydrogel enhances implant osseointegration in cancellous bone

“…45 Peplow et al 46 suggested that porous keratin matrices might be used as scaffolds in tissue repair or regeneration, while matrices with little or no porosity might serve to stabilize fractured bone or be used as bone anchors. Dias et al 47 subsequently implanted 3 mm diameter porous keratin cylindrical scaffolds containing 40% hydroxyapatite, into proximal condyle and mid-shaft sites in sheep tibia, with healing periods ranging from 1 to 12 weeks. New bone ingrowth reached the center of the cylinder by 4 weeks, however osteoid regeneration was 3 to 3.5 times slower than sham-operated unfilled control sites or defects filled with collagen.…”

Biomaterial Properties Modulating Bone Regeneration

“…[ 27–29 ] Organic polymers consist of proteins such as: collagen, [ 30–32 ] gelatin, [ 33 ] elastin, [ 34 ] silk, [ 35 ] fibrin, [ 36,37 ] and keratin. [ 38 ] Polysaccharides such as chitosan, [ 39–41 ] hyaluronic acid, [ 42 ] alginic acid, [ 43,44 ] cellulose, [ 45,46 ] and chondroitin sulfate [ 47,48 ] are also commonly used. These materials usually demonstrate excellent biocompatibility and biodegradability.…”