Al-Maawi Sarah, Barbeck Mike, -Vizcaíno Carlos Herrera, Egli Rainer, Sader Robert, Kirkpatrick Charles James, Bohner Marc, Ghanaati Shahram
Frankfurt Orofacial Regenerative Medicine (FORM) Lab, Department for Oral, Cranio-Maxillofacial and Facial Plastic Surgery, Medical Center of Goethe University Frankfurt, Germany.
Department of Oral and Maxillofacial Surgery, Working Group Biomaterials/Surfaces, University Hospital Hamburg-Eppendorf, Hamburg, 20246, Germany.
Acta Biomater. 2021 Feb;121:621-636. doi: 10.1016/j.actbio.2020.11.034. Epub 2020 Nov 26.
Evaporation of phosphate species during thermal treatment (> 400 °C) of calcium phosphates leads to the formation of an alkaline layer on their surface. The aim of this study was to evaluate the hypothesis that the biological response of thermally treated calcium phosphates is modified by the presence of such an alkaline layer on their surface. For this purpose, 0.125-0.180 mm α- and β-tricalcium phosphate (TCP) granules were obtained by crushing and size classification, with some being subjected to thermal treatment at 500 °C. The four types of granules (α-TCP, β-TCP, α-TCP-500 °C, and β-TCP-500 °C) were implanted subcutaneously and orthotopically in rats. Sham operations served as control. Subcutaneously, α-TCP and β-TCP induced significantly more multinucleated giant cells (MNGCs) than calcined granules. Most of the induced MNGCs were TRAP-negative, CD-68 positive and cathepsin K-negative, reflecting a typical indication of a reaction with a foreign body. The vessel density was significantly higher in the α-TCP and β-TCP groups than it was in the α-TCP-500 °C and β-TCP-500 °C groups. In the femur model, β-TCP-500 °C induced significantly more new bone formation than that induced by β-TCP. The granule size was also significantly larger in the β-TCP-500 °C group, making it more resistant to degradation than β-TCP. The MNGC density was higher in the α-TCP and β-TCP groups than in the α-TCP-500 °C and β-TCP-500 °C groups, including cathepsin-positive, CD-68 positive, TRAP-positive and TRAP-negative MNGCs. In conclusion, this study confirms that the biological response of calcium phosphates was affected by the presence of an alkaline layer on their surface. Thermally-treated α-TCP and β-TCP granules produced significantly fewer MNGCs and were significantly less degraded than non-thermally-treated α-TCP and β-TCP granules. Thermally treating α-TCP and β-TCP granules shifts the reaction from a foreign body reaction towards a physiological reaction by downregulating the number of induced MNGCs and enhancing degradation resistance.
磷酸钙在热处理（>400°C）过程中磷酸盐物种的蒸发导致其表面形成碱性层。本研究的目的是评估这样一种假设，即热处理后的磷酸钙的生物学反应会因其表面存在这种碱性层而发生改变。为此，通过粉碎和尺寸分级获得了0.125 - 0.180毫米的α - 和β - 磷酸三钙（TCP）颗粒，其中一些颗粒在500°C下进行了热处理。将四种类型的颗粒（α - TCP、β - TCP、α - TCP - 500°C和β - TCP - 500°C）皮下和原位植入大鼠体内。假手术作为对照。在皮下，α - TCP和β - TCP诱导产生的多核巨细胞（MNGC）明显多于煅烧颗粒。诱导产生的大多数MNGC是抗酒石酸酸性磷酸酶（TRAP）阴性、CD - 68阳性且组织蛋白酶K阴性，这反映了与异物反应的典型特征。α - TCP和β - TCP组的血管密度明显高于α - TCP - 500°C和β - TCP - 500°C组。在股骨模型中，β - TCP - 500°C诱导的新骨形成明显多于β - TCP诱导的新骨形成。β - TCP - 500°C组的颗粒尺寸也明显更大，使其比β - TCP更耐降解。α - TCP和β - TCP组的MNGC密度高于α - TCP - 500°C和β - TCP - 500°C组，包括组织蛋白酶阳性、CD - 68阳性、TRAP阳性和TRAP阴性的MNGC。总之，本研究证实磷酸钙的生物学反应受到其表面碱性层的影响。热处理后的α - TCP和β - TCP颗粒产生的MNGC明显较少，并且比未热处理的α - TCP和β - TCP颗粒降解明显更少。对α - TCP和β - TCP颗粒进行热处理通过下调诱导产生的MNGC数量并增强抗降解性，使反应从异物反应转变为生理反应。
