Preparation and Characterization of Surface Heat Sintered Nanohydroxyapatite and Nanowhitlockite Embedded Poly (Lactic-co-glycolic Acid) Microsphere Bone Graft Scaffolds: In Vitro and in Vivo Studies.

Gils Jose,Jyh-Ping Chen,K T Shalumon,Han-Tsung Liao,Chang-Yi Kuo

doi:10.3390/ijms21020528

Abstract

In the context of using bone graft materials to restore and improve the function of damaged bone tissues, macroporous biodegradable composite bone graft scaffolds have osteoinductive properties that allow them to provide a suitable environment for bone regeneration. Hydroxyapatite (HAP) and whitlockite (WLKT) are the two major components of hard tissues such as bone and teeth. Because of their biocompatibility and osteoinductivity, we synthesized HAP (nHAP) and WLKT nanoparticles (nWLKT) by using the chemical precipitation method. The nanoparticles were separately incorporated within poly (lactic-co-glycolic acid) (PLGA) microspheres. Following this, the composite microspheres were converted to macroporous bone grafts with sufficient mechanical strength in pin or screw shape through surface sintering. We characterized physico-chemical and mechanical properties of the nanoparticles and composites. The biocompatibility of the grafts was further tested through in vitro cell adhesion and proliferation studies using rabbit bone marrow stem cells. The ability to promote osteogenic differentiation was tested through alkaline phosphate activity and immunofluorescence staining of bone marker proteins. For in vivo study, the bone pins were implanted in tibia bone defects in rabbits to compare the bone regeneration ability though H&E, Masson’s trichrome and immunohistochemical staining. The results revealed similar physico-chemical characteristics and cellular response of PLGA/nHAP and PLGA/nWLKT scaffolds but the latter is associated with higher osteogenic potential towards BMSCs, pointing out the possibility to use this ceramic nanoparticle to prepare a sintered composite microsphere scaffold for potential bone grafts and tissue engineered implants.

Highlights

Bone fractures and bone disorders among middle aged people are increasing day by day, which demands the development of suitable bone grafts as an essential prerequisite to fix bone defects.Recent advancements in bone graft materials including polylactide, titanium, and hydroxyapatite (HA) have led to the introduction of various products including bone plates and biodegradable bone pins that can cure many bone defects [1,2]
The morphology of prepared nanosized HAP (nHAP) and nWLKT particles was analyzed using scanning electron microscopy (SEM) analysis, from which particles were found to be uniform in size and shape, and with minimum agglomeration (Figure 2A,B)
The elemental compositions of both samples were identified through energy dispersive X-ray spectroscopy (EDS) analysis

Summary

Introduction

Bone fractures and bone disorders among middle aged people are increasing day by day, which demands the development of suitable bone grafts as an essential prerequisite to fix bone defects.Recent advancements in bone graft materials including polylactide, titanium, and hydroxyapatite (HA) have led to the introduction of various products including bone plates and biodegradable bone pins that can cure many bone defects [1,2]. Many bone grafts and similar tissue engineering scaffolds possess biodegradability, biocompatibility, and adequate mechanical strength, their ability to reconstruct defected areas has not been very high in many experiments [3]. Osteobiologic materials are engineered biomaterials that can serve as implant materials for bone repair and remodeling. Due to the capacity of these osteobiologic materials to promote the healing of bone fractures, they have been the most discussed biomaterials in the past decade [4]. The osteobiologic materials are expected to provide a biocompatible surface that can promote cell attachment and migration after implantation. Due to the similarities of these materials with the body, the scaffolds made of osteobiologic materials can mimic the bodies’ inherent capacity to heal defects and to regenerate bone tissues [5]. Nanoparticles prepared from these bioceramic materials can further enhance their physical as well as biological properties, due to the greater surface area provided [9,10]

Methods

Results

Conclusion