Bioactive Glass for Large Bone Repair

Abstract

There has been an ongoing quest for new biomedical materials for the repair and regeneration of large segmental bone defects caused by disease or trauma. Autologous bone graft (ABG) remains the gold standard for bone repair despite their limited supply and donor-site morbidity. The current tissue engineering approach with synthetically derived bone grafts requires a bioactive ceramic or polymeric scaffold loaded with growth factors for osteoinduction and angiogenesis, and bone marrow stromal cells (BMSCs) for osteogenic properties. Unfortunately, this approach has serious drawbacks: the low mechanical strength of scaffolds, the high cost of growth factors, and a lack of optimal strategies for growth-factor delivery. Here, it is shown that, for the first time, a synthetic material alone can repair large bone defects as efficiently as the gold standard ABG. Through the use of strong and resorbable bioactive glass scaffolds, complete bone healing, and defect bridging can be achieved in a rabbit femur segmental defect model without growth factors or BMSCs. New bone and blood vessel formation, in both inner and peripheral scaffolds, demonstrates the excellent osteoinductive and osteogenic properties of these scaffolds similar as ABG.

Tough and strong porous bioactive glass-PLA composites for structural bone repair

“…Scaffolds of 13–93 glass with a similar microstructure have also shown the capacity to heal segmental defects in rabbit femurs [14]. Bioactive glass (13–93) scaffolds with the L4S1 structure (without a PLA layer) have a higher compressive strength (88 ± 20 MPa) and a significantly higher flexural strength of (34 ± 5 MPa) than the scaffolds used in those studies.…”

“…Despite a low flexural strength (10 to 15 MPa), much smaller than that of cortical bone (100 to 150 MPa) [9], these strong porous scaffolds have shown the ability to repair critical size segmental defects in a rat or rabbit femoral model [13, 14]. Modification of the grid-like microstructure to produce a porosity gradient in the scaffolds resulted in a significant improvement in the flexural strength (34 ± 5 MPa) without sacrificing the ability to support bone infiltration [15].…”

Review - bioactive glass implants for potential application in structural bone repair

“…In another study [30], scaffolds with a uniform gridlike microstructure composed of 13-93 glass (porosity = 50%; pore width = 200 µm; compressive strength = 80 MPa) and 2B6Sr glass (porosity = 50%; pore width = 200 µm; compressive strength = 36 MPa) were implanted in rabbit femoral segmental defects (10 mm in length × 6 mm in diameter) for 3 and 9 months. Autogeneous bone grafts and the empty defects were used as the positive and negative control group, respectively.…”

“…These scaffolds were shown to have a microstructure conducive to infiltration with new bone [26,27], elicited no adverse biological reaction over a long-term period in vivo (6 months) [26,28], and healed critical-size segmental defects in small and large rodents [29,30]. Loading these strong porous scaffolds with an osteogenic growth factor significantly enhanced the rate of bone healing [26].…”

Bioactive Pore‐Forming Bone Adhesives Facilitating Cell Ingrowth for Fracture Healing

“…The incorporation of bioactive components is another way to improve the biological performance of bone adhesives. Among these, bioactive glass (BG) mainly composed of silicon and calcium elements has proven their osteoinductive and osteoconductive capabilities . BG is found to induce the generation of a hydroxyapatite (HA) layer chemically bonding to the bone under physiological condition during degradation .…”