Optimization of poly (lactic-co-glycolic acid)-bioactive glass composite scaffold for bone tissue engineering using stem cells from human exfoliated deciduous teeth

Highlights

• 10 % bioactive glass in PLGA scaffold is suitable ratio for bone tissue engineering.

• Successfully produces PLGA/bioactive glass scaffold using salt-leaching technique.

• SHED have been considered as alternative sources for cleft patient treatment.

Abstract

Objective

The aim of this study was to develop a composite scaffold with the optimal poly(lactic-co-glycolic acid) (PLGA) and bioactive glass proportions to provide an environment for bone tissue regeneration and repair.

Design

PLGA-bioactive glass composite scaffolds were prepared using a salt-leaching technique with different percentages of bioactive glass (0%, 10 %, and 15 % [w/w]) with PLGA. The resulting scaffolds were characterized using scanning electron microscopy and energy dispersive X-ray spectroscopy (SEM-EDS), and water contact angle, dynamic mechanical, and pH analysis. The scaffold biocompatibility was investigated using stem cells from human exfoliated deciduous teeth (SHED) and rat experiments.

Results

SEM-EDS confirmed the successful fabrication of three-dimensional PLGA-bioactive glass scaffolds. The results showed that 10 % bioactive glass with PLGA exhibited favorable properties including increased pore size, hydrophilicity, and mechanical properties. The growth medium pH was increased for scaffolds containing bioactive glass. All scaffolds were biocompatible, and 10 % bioactive glass composite scaffolding showed better attachment, growth, and proliferation of SHED compared to the other scaffolds. Moreover, it enhanced osteogenic differentiation of SHED in vitro and in vivo.

Conclusions

Salt-leaching-derived PLGA-bioactive glass composite scaffolds were successfully established. PLGA with 10 % bioactive glass had adequate physical properties and bioactivity, and it could be considered as a composite for bone tissue engineering applications.

Introduction

Bone loss is a significant consequence that results from various diseases such as periodontal disease and bone tumors, which are major concerns for public health (Pneumaticos, Triantafyllopoulos, Basdra, & Papavassiliou, 2010). Clinically, bone grafts are used as a gold standard treatment to augment bone regeneration and repair (Pneumaticos et al., 2010). However, a bone graft can cause adverse events such as inadequate bone formation, more donor site morbidity, and immune rejection (Amini, Laurencin, & Nukavarapu, 2012; Roseti et al., 2017). To address all these issues, bone tissue engineering including scaffolds, stem cells, and growth factors should be emphasized as an alternative method. Scaffolding has been designed to mimic the natural extracellular matrix and it must provide more space to facilitate the exchange of nutrients/oxygen and be biocompatible enough to provide a suitable environment for cell proliferation/differentiation (Bakhtiar et al., 2020; Yang, Liu, Fang, Chen, & Chen, 2019).

Bioactive glass is widely used as a bioactive material to improve or support the healing process of bone injuries because of its ionic dissolution products. The bioactive glass dissolution products are directly released in the physiological environment, and they strongly bond the host tissue and form an interfacial calcium phosphate layer (Fiume, Barberi, Verne, & Baino, 2018). However, the main drawback of bioactive glass is its intrinsic brittleness, causing frequent cracks or fractures (Kim et al., 2019). Poly lactic-co-glycolic acid (PLGA) is a synthetic polymer that is widely used as a medical engineering material because of its biocompatibility and biodegradability, and is approved by the FDA (Yao, Radin, Leboy, & Ducheyne, 2005). Bioactive glass combined with PLGA can reduce the disadvantages of each other (Yang et al., 2019; Yao et al., 2005)

Stem cells from human exfoliated deciduous teeth (SHED) are self-renewable and multipotential cells that can commit to the osteoblast lineage (Miura et al., 2003). SHED have been reported to repair calvarial defects in mice (Demarco et al., 2011). Moreover, these cells are ethically acceptable, noninvasive, less dependent on timing, and far less expensive. Yao et al., produced PLGA/bioactive glass microspheres by modified emulsification method (Yao et al., 2005). They showed that the composite scaffolds can promote osteogenic differentiation from rat marrow stromal cells and increase alkaline phosphatase activity. Moreover, Boccaccini et al., and Yang et al., fabricated PLGA/bioactive glass by thermally induced phase separation method (Boccaccini, Notingher, Maquet, & Jerome, 2003; Yang et al., 2019). The addition of bioactive glass to the scaffold enhances adhesion and proliferation of human osteosarcoma cell line, as well as promoting cell osteogenesis (Yang et al., 2019).

Although bioactive glass combined with PLGA has been reported in several studies (Boccaccini et al., 2003; Yang et al., 2019; Yao et al., 2005), the proper ratio of bioactive glass to PLGA composite scaffolds are still controversial. The purpose of this study was to discover the most appropriate ratio of PLGA-bioactive glass composite scaffold for bone tissue engineering. PLGA-bioactive glass composite scaffold was prepared using a salt-leaching technique with different ratios of bioactive glass, such as 0%, 10 %, and 15 % (w/w), with PLGA. The scaffolds were evaluated for their characteristics and their physical and mechanical properties. SHED were used to examine the in vitro and in vivo biocompatibility of the scaffolds.