Sequential sequestrations increase the incorporation and retention of multiple growth factors in mineralized collagen scaffolds

Abstract

Trauma induced injuries of the mouth, jaw, face, and related structures present unique clinical challenges due to their large size and complex geometry. Growth factor signaling coordinates the behavior of multiple cell types following an injury, and effective coordination of growth factor availability within a biomaterial can be critical for accelerating bone healing. Mineralized collagen scaffolds are a class of degradable biomaterial whose biophysical and compositional parameters can be adjusted to facilitate cell invasion and tissue remodeling. Here we describe the use of modified simulated body fluid treatments to enable sequential sequestration of bone morphogenic protein 2 and vascular endothelial growth factor into mineralized collagen scaffolds for bone repair. We report the capability of these scaffolds to sequester growth factors from solution without additional crosslinking treatments and show high levels of retention for individual and multiple growth factors that can be layered into the material via sequential sequestration steps. Sequentially sequestering growth factors allows prolonged release of growth factors in vitro and suggests the potential to improve healing of large-scale bone injury models in vivo. Future work will utilize this sequestration method to induce cellular activities critical to bone healing such as vessel formation and cell migration.

Evaluation of P. aeruginosa attachment on mineralized collagen scaffolds and addition of manuka honey to increase mesenchymal stem cell osteogenesis

“…Release of glucose and MGO suggest that soaking already fabricated scaffolds in honey solution was the better method to facilitate release of honey from the scaffold into the surroundings; however, quantifying the total amount of honey released also suggested that even for honey soaked scaffolds, the majority of the honey was retained in the scaffold. These findings were also consistent with prior work to sequester growth factors within the mineralized collagen scaffolds, which also identified a significant fraction was retained within the scaffold [57]. The pH of honey soaked and incorporated scaffolds was also assessed, as mineralized collagen scaffolds have been known to release mineral over time and causing a reduction in pH, with honey also known to have a low pH [30, 60].…”

“…After sterilization, scaffolds were handled following sterile procedures in a biosafety cabinet. Scaffolds were hydrated following previously described procedures [49, 50, 53–57]. Briefly, scaffolds were hydrated in 100% ethanol, then in multiple washes with PBS, and then crosslinked with carbodiimide chemistry in PBS solution:1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC, Sigma-Aldrich) and N-hydroxysuccinimide (NHS, Sigma-Aldrich) at a molar ration of 5:2:1 EDAC:NHS:COOH, with carboxylic acid groups present on the collagen backbone.…”

“…Statistical analysis of samples followed guidelines by Ott and Longnecker and previous experiments with similar sample groups [49, 57, 60, 64–66]. All samples were assessed for normality with a Shapiro-Wilk test and equal variance with a Levene test prior to statistical analysis.…”

Soluble extracts from amnion and chorion membranes improve hMSC osteogenic response in a mineralized collagen scaffold

“…These meshes do not influence scaffold microarchitecture or negatively affect cell activity in scaffolds and were not included in this study as we focused on modification to scaffold composition. We also reported mineralized collagen scaffolds soaked in media containing soluble biomolecules efficiently sequestered these biomolecules within the scaffold microarchitecture [55], with matrix charge and mineral content suspected to enhance sequestration.…”

“…We have previously shown that mineralized collagen scaffolds can sequester 60-90% of growth factors from solution [36]. As OPG plays a vital role in osteoclastogenesis inhibition and was found to be released in high levels from both membranes, we subsequently examined OPG release profiles of incorporated and soaked scaffolds comparing results to the conventional mineralized collagen scaffold (MC).…”