Tetracalcium Phosphate Biocement Hardened with a Mixture of Phytic Acid-Phytase in the Healing Process of Osteochondral Defects in Sheep.

Hyaline articular cartilage has unique physiological, biological, and biomechanical properties with very limited self-healing ability, which makes the process of cartilage regeneration extremely difficult. Therefore, research is currently focused on finding new and potentially better treatment options. The main objective of this in vivo study was to evaluate a novel biocement CX consisting of tetracalcium phosphate-monetit biocement hardened with a phytic acid-phytase mixture for the regeneration of osteochondral defects in sheep. The results were compared with tetracalcium phosphate-monetit biocement with classic fast-setting cement systems and untreated defects. After 6 months, the animals were sacrificed, and the samples were evaluated using macroscopic and histologic methods as well as X-ray, CT, and MR-imaging techniques. In contrast to the formation of fibrous or fibrocartilaginous tissue on the untreated side, treatment with biocements resulted in the formation of tissue with a dominant hyaline cartilage structure, although fine fibres were present (p < 0.001). There were no signs of pathomorphological changes or inflammation. Continuous formation of subchondral bone and hyaline cartilage layers was present even though residual biocement was observed in the trabecular bone. We consider biocement CX to be highly biocompatible and suitable for the treatment of osteochondral defects.

Pharmacological activation of estrogen receptors-α and -ß differentially modulates keratinocyte differentiation with functional impact on wound healing.

Estrogen deprivation is considered responsible for many age-related processes, including poor wound healing. Guided by previous observations that estradiol accelerates re­epithelialization through estrogen receptor (ER)­ß, in the present study, we examined whether selective ER agonists [4,4',4''-(4-propyl [1H] pyrazole-1,3,5-triyl)­trisphenol (PPT), ER­α agonist; 2,3-bis(4-hydroxyphenyl)-propionitrile (DPN), ER­ß agonist] affect the expression of basic proliferation and differentiation markers (Ki­67, keratin­10, ­14 and ­19, galectin­1 and Sox­2) of keratinocytes using HaCaT cells. In parallel, ovariectomized rats were treated daily with an ER modulator, and wound tissue was removed 21 days after wounding and routinely processed for basic histological analysis. Our results revealed that the HaCaT keratinocytes expressed both ER­α and ­ß, and thus are well-suited for studying the effects of ER agonists on epidermal regeneration. The activation of ER­α produced a protein expression pattern similar to that observed in the control culture, with a moderate expression of Ki­67 being observed. However, the activation of ER­ß led to an increase in cell proliferation and keratin­19 expression, as well as a decrease in galectin­1 expression. Fittingly, in rat wounds treated with the ER­ß agonist (DPN), epidermal regeneration was accelerated. In the present study, we provide information on the mechanisms through which estrogens affect the expression patterns of selected markers, thus modulating keratinocyte proliferation and differentiation; in addition, we demonstrate that the pharmacological activation of ER-α and -ß has a direct impact on wound healing.