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Keratin, a fibrous protein, that is available from a variety of animal sources as a constituent of hair, nails, horns, hoofs, wool and feathers, has applications in pharmaceutics, cosmetics and as a fertilizer. Like many naturally-derived biomaterials, the intrinsic biological activity and biocompatibility of keratin render this polymer a potential candidate for applications in medicine, and for the fabrication of scaffolds for tissue engineering. While several sources of keratin can be considered, the bioactivity of the keratins obtained can be quite different. In this study we discuss the processing and characterization of keratin from camel hair and goat cashmere. Specifically, the camel hair and cashmere were dissolved in an ionic liquid (1-butyl-3-methylimidazolium chloride), and the characteristics of the soluble and insoluble keratin were evaluated. The structure and properties of the raw material, soluble, and insoluble keratin were studied. Compared to the starting material, the soluble keratin showed chemical changes viz. decrease of cysteine, and minor structural changes. Preliminary in vitro biological properties performed by a lactate dehydrogenase (LDH) assay and scratch test showed good bioactivity in keratin from both sources. In particular, cell migration was observed to be faster when cells were cultured in the presence of soluble keratin extracted from camel hair and cashmere.

The development of a biomaterial substitute that can promote bone regeneration in massive defects has remained as a significant clinical challenge even using bone marrow cells or growth factors. Without an active, thriving cell population present throughout and stable anchored to the construct, exceptional bone regeneration does not occur. An engineered micro-channel structures scaffold within each trabecular has been designed to overcome some current limitations involving the cultivation and habitation of cells in large, volumetric scaffolds to repair massive skeletal defect. We created a scaffold with a superior fluid retention capacity that also may absorb bone marrow cells and provide growth factor-containing body fluids such as blood clots and/or serum under physiological conditions. The scaffold is composed of 3 basic structures (1) porous trabecular network (300-400 μm) similar to that of human trabecular bones, (2) micro-size channels (25-70 μm) within each trabecular septum which mimic intra-osseous channels such as Haversian canals and Volkmann's canals with body fluid access, diffusion, nutritional supply and gas exchange, and (3) nano-size pores (100-400 nm) on the surface of each septum that allow immobilized cells to anchor. Combinatorial effects of these internal structures result in a host-adapting construct that enhances cell retention and habitation throughout the 3 cm-height and 4 cm-length bridge-shaped scaffold.

Heterotopic ossification is one of the possible complications following cervical total disk replacement. Although there are numerous hypotheses regarding the etiology of heterotopic ossification, the main causes of heterotopic ossification remain unknown. In this study, we hypothesize that heterotopic ossification formation is related to external loading in the cervical vertebrae after total disk replacement. A two-dimensional finite element model of a cervical vertebra treated by total disk replacement in the sagittal plane was developed. The bone adaptation process of heterotopic ossification was simulated based on strain energy density under both compressive and shear forces. Different types of heterotopic ossification formation were analyzed according to the directions of forces. Two distinct types of heterotopic ossification following cervical total disk replacement were predicted, which was consistent with previous clinical studies. Type 1 heterotopic ossification was observed in the posterior upper part of the vertebra under compressive forces, while type 2 heterotopic ossification was detected mostly in the anterior upper part under shear forces. In addition, heterotopic ossification formation enhanced the strain energy distribution, which is known to be related to bone remodeling. This article presents the effects of different mechanical loading conditions on the occurrence of heterotopic ossification following cervical total disk replacement, and the results may be useful for the design of artificial disks that minimize heterotopic ossification.

We have developed a hydroxyapatite-based scaffold with micro-channels and nano-pores (MCNP) using a polyurethane template coating method to overcome some of the limitations by addressing fluid absorbance and retention via capillary action. The novel scaffold has 3 basic structures. First, the scaffold has a porous trabecular network similar to that of human trabecular bones (300–400 um) which are mechanically matched to the strength of native trabecular bone (2–12 MPa). Second, it has micro-sized channels (25–70 um) within each trabecular septum which exhibit highly effective fluid absorption via capillary action. Third, the surface of each septum has nano-sized pores (100–400 nm) that allow immobilized cells to anchor. The surface area of the scaffold with micro-channels was significantly (+42.0%) higher than the scaffold without micro-channels as calculated using computer aided design (CAD) software, while overall porosity did not change significantly (+8.8%). Combinatorial effects of these internal structures result in a host-adapting construct that enhances cell ingress and retention from the host bone marrow throughout the entire scaffold.