Cell seeding into calcium phosphate cement

Abstract

To improve the effectiveness of calcium phosphate cement (CPC), we have developed a method to seed osteoblasts into the cement. CPC powder is mixed with water to form a paste that can be shaped to fit a bone defect in situ. The paste hardens in 30 min, reacts to form hydroxyapatite, and is replaced with new bone. Reacted CPC is biocompatible but unreacted CPC paste was found to have toxic effects when placed on cell monolayers (MC3T3-E1 cells). In contrast, when cells were indirectly exposed to CPC paste using a porous membrane or by placing a coverslip containing adherent cells onto a bed of CPC paste, the unreacted CPC was nontoxic. These results suggested that gel encapsulation of the cells might protect them from the CPC paste. Thus, cells were encapsulated in alginate beads (3.6-mm diameter), mixed with CPC paste, and incubated overnight. Both vital staining (calcein-AM and ethidium homodimer-1) and the Wst-1 assay (measures dehydrogenase activity) showed that cell survival in alginate beads that were mixed with CPC was similar to survival in untreated control beads. These results suggest that gel encapsulation could be used as a mechanism to protect cells for seeding into CPC.

Fast-Degradable Microbeads Encapsulating Human Umbilical Cord Stem Cells in Alginate for Muscle Tissue Engineering

“…Color images available online at www.liebertpub.com/tea shown to degrade and did not release the cells. 47,48 Another study developed RGD-modified alginate microbeads of 1 mm in diameter, but bead degradation and cell release were not mentioned. 49 A recent study fabricated alginate microbeads of approximately 200 mm for cell encapsulation; no microbead degradation or cell release was reported.…”

Delivering MC3T3-E1 cells into injectable calcium phosphate cement through alginate-chitosan microcapsules for bone tissue engineering

“…Then, 200 μl of AC-cell microcapsules were thoroughly mixed with fresh CPC paste. The ratio of the volume of microcapsules to the total volume of CPC plus microcapsules was approximately 50% (Simon et al, 2004;Deville et al, 2006;Weir et al, 2006;Zhao et al, 2010a;2010b). Following incubation for 15 min (initial setting time, I-ST) (van den Vreken et al, 2010), 1.5 ml of fresh medium was added into each well until the construct was completely submerged.…”

“…To improve the effectiveness of CPCs, osteoblasts and stem cells embedded within alginate beads have been seeded into CPC paste and alginate hydrogel has been shown to protect the implanted cells from the mixing and injection forces, as well as from the CPC setting reaction (Simon et al, 2004;Weir et al, 2006;Weir and Xu, 2010;Xu et al, 2010;Zhao et al, 2010a;2010b;2011). However, the implanted cells could not be released from the alginate beads or attached onto the CPC.…”

Sustainable Materials and Biorefinery Chemicals from Agriwastes

“…Autografts are used to treat these defects, but available bone can be inadequate and difficult to shape and obtain. Allografts and xenografts must be processed to eliminate the risk of transmission of live viruses [40]. These difficulties have been the impetus for research into a variety of bone grafting materials.…”