Poly(lactic acid-co-glycolic acid)-based celecoxib extended-release microspheres for the local treatment of traumatic heterotopic ossification

Traumatic heterotopic ossification (THO) is a serious and common clinical post-traumatic complication for which there is no effective and safe drug treatment. Routine administration of nonsteroidal anti-inflammatory drugs (NSAIDs) after injury is extensively used approach for THO. However, serious adverse events can occur in the event of an overdose of NSAIDs. In our study, we have developed a poly(lactic acid-co-glycolic acid) (PLGA) microsphere by emulsifying solvent volatilization for the prolonged slow delivery of celecoxib (CLX). Three groups of celecoxib-poly(lactic acid-co-glycolic acid) microspheres (CLX–PLGA MPs) were prepared with particle sizes of 3.75±1.28 μm, 49.56±17.15 μm, and 94.98±42.53 μm. Meanwhile, related parameters of microspheres in each group were studied: drug loading (DL), encapsulation rate (EE), and slow-release behavior. The DL and EE of the 3 CLX–PLGA MPs did not vary significantly, and subsequently, we selected the second drug loading microspheres with a retardation period of about 70 days for subsequent experiments. Moreover, cellular and animal experiments suggest that the microspheres are biocompatible and can be safely applied to localized trauma tissue. Finally, it is demonstrated that CLX–PLGA MPs have an effect on inhibiting the osteogenic differentiation of bone marrow mesenchymal stem cells and have the potential to inhibit ectopic bone formation of the THO model in Sprague-Dawley rat. Therefore, this study suggests that CLX–PLGA MPs are expected to be applied topically in the early post-traumatic period to prevent the development of THO.