Structural properties and electron spin resonance (ESR) dose estimations of fossil cow tooth enamel from Kösk Höyük, Turkey.

In this work, two cow teeth collected from the Nigde-Kösk Höyük excavation site in Turkey were studied for characterization and dosimetric purposes. Each tooth sample was prepared by applying mechanical and chemical methods to obtain the enamel fractions. To do this, mineralogical and elemental concentration properties of the tooth enamels were investigated by performing X-ray diffraction (XRD) and scanning electron microscopy coupled with energy-dispersive X-ray measurements (SEM-EDX). It was found that the enamel structures contained a highly hydroxyapatite crystalline without any characteristic impurities. The dose response of the tooth enamels was determined by using the electron spin resonance (ESR) method. Absorbed radiation doses were calculated as (26.05 ± 0.15) Gy and (25.48 ± 0.18) Gy by the additive dose method using both natural radiation doses and artificial irradiation doses of the enamel samples. It is concluded that these samples could be used to reconstruct radiation doses. This result can be considered as a precursor for future ESR dosimetry/dating studies of other fossil teeth at this excavation site.

Preliminary assessment of an injectable extracellular matrix from decellularized bovine myocardial tissue.

The goal of this study was to develop an injectable form of decellularized bovine myocardial tissue matrix which could retain high levels of functional ECM molecules, and could gel at physiological temperature. Dissected ventricular tissue was processed by a detergent-based protocol, lyophilized, enzymatically-digested, and neutralized to form the injectable myocardial matrix (IMM). Histochemical analysis, DNA quantification, and agarose gel electrophoresis demonstrated the efficiency of the applied protocol. Chemical, thermal, morphological, and rheological characterization; protein and sulfated glycosaminoglycan (sGAG) content analysis were performed, in vitro biological properties were evaluated. An in vivo histocompatibility and biodegradability study was performed. Histochemistry revealed complete removal of myocardial cells. DNA content analysis revealed a significant decrease (87%) in the nuclear material, while protein and sGAG contents were highly preserved following decellularization. Soluble IMM was capable of turning into gel form at ∼37 °C, indicating selfassembling property. In vitro findings showed the biomaterial was noncytotoxic, nonhemolytic, and supported the attachment and proliferation of mesenchymal stem cells. In vivo study demonstrated IMM was well-tolerated by rats receiving subcutaneous injection. This work demonstrates that the IMM from decellularized bovine myocardial tissue has the potential for use as a feasible regenerative biomaterial in prospective tissue engineering and regenerative medicine studies.

Clinical Applications of Injectable Biomaterials.

Regenerative medicine is an interdisciplinary field that aims to regenerate the lost or diseased tissues through the combinational use of cells, biomolecules and/or biomaterials. Injectable biomaterials have been comprehensively evaluated for use in this field for their prominent properties, such as ease of handling, providing a better integration of the native tissue by filling irregular defects and having controllable chemical and physical properties. This class of biomaterials can be developed from natural or synthetic origin materials, decellularized matrices or from combinations of materials to form composites. Injectable biomaterials enable minimally invasive approach when compared with traditional open surgeries, which can reduce the cost, and speed up the recovery time for the patients. Cells, growth factors and/or bioactive molecules can be effectively delivered to the target tissue using injectable biomaterials, making them desirable for a number of clinical applications. This chapter gives an overview on injectable biomaterials and their clinical applications in soft, hard, and cardiovascular tissue regeneration.