Generation of composites for bone tissue-engineering applications consisting of gellan gum hydrogels mineralized with calcium and magnesium phosphate phases by enzymatic means

Abstract

Mineralization of hydrogels, desirable for bone regeneration applications, may be achieved enzymatically by incorporation of alkaline phosphatase (ALP). ALP-loaded gellan gum (GG) hydrogels were mineralized by incubation in mineralization media containing calcium and/or magnesium glycerophosphate (CaGP, MgGP). Mineralization media with CaGP:MgGP concentrations 0.1:0, 0.075:0.025, 0.05:0.05, 0.025:0.075 and 0:0.1 (all values mol/dm , denoted A, B, C, D and E, respectively) were compared. Mineral formation was confirmed by IR and Raman, SEM, ICP-OES, XRD, TEM, SAED, TGA and increases in the the mass fraction of the hydrogel not consisting of water. Ca was incorporated into mineral to a greater extent than Mg in samples mineralized in media A-D. Mg content and amorphicity of mineral formed increased in the order A < B < C < D. Mineral formed in media A and B was calcium-deficient hydroxyapatite (CDHA). Mineral formed in medium C was a combination of CDHA and an amorphous phase. Mineral formed in medium D was an amorphous phase. Mineral formed in medium E was a combination of crystalline and amorphous MgP. Young's moduli and storage moduli decreased in dependence of mineralization medium in the order A > B > C > D, but were significantly higher for samples mineralized in medium E. The attachment and vitality of osteoblastic MC3T3-E1 cells were higher on samples mineralized in media B-E (containing Mg) than in those mineralized in medium A (not containing Mg). All samples underwent degradation and supported the adhesion of RAW 264.7 monocytic cells, and samples mineralized in media A and B supported osteoclast-like cell formation. Copyright © 2014 John Wiley & Sons, Ltd.

High‐resolution synchrotron X‐ray analysis of bioglass‐enriched hydrogels

“…The fact that the areas with cells were roughly spherical suggests that that rMSC adhesion only took place on bioglass particles or aggregates. This observation is in agreement with the findings in previous publications, in which MC3T3‐E1 osteoblast‐like cells displayed poor adhesion on pure GG hydrogels but adhered much better to GG hydrogels enzymatically mineralized with CaP and magnesium‐enriched CaP . In previous work, pure GG hydrogels did not mineralize with apatite upon incubation in SBF, but apatite formed on both GG‐A2 and GG‐S2 hydrogel–bioglass composites .…”

Mineralization of gellan gum hydrogels with calcium and magnesium carbonates by alternate soaking in solutions of calcium/magnesium and carbonate ion solutions

“…This suggests an increasing amorphicity in the direction A➔E. Characteristic bands for GG at approximately 1,600 and 1,030 cm −1 , which were detected in previous works (Douglas, Krawczyk, et al, , Douglas, Wlodarczyk, et al, , Douglas et al, ), were not observed in any sample group. This demonstrates that a relatively small amount of GG was present relative to the carbonate mineral.…”

“…Recently, inorganic calcium phosphate (CaP)‐based materials for bone regeneration have been enriched to promote adhesion and proliferation of bone‐forming cells (Bracci et al, , Douglas, Krawczyk, et al, , Landi et al, ). Hence, on the basis of these studies, it was speculated in our study that CaCO 3 enrichment with Mg could lead to similar positive biological effects.…”

Cell-laden hydrogels for osteochondral and cartilage tissue engineering

“…After 42-day culture in chondrogenic medium, cartilaginous ECM components of aggrecan and collagen type II were produced with the confirmation of chondrocytic gene expression [146]. Gellan gum hydrogels incorporated with bioglass/bioceramic particles or bone-forming growth factors were shown to support encapsulation, proliferation, and osteogenesis of preosteoblasts and MSCs for bone tissue regeneration [147–149]. Although gellan gum hydrogels are promising for cartilage and bone tissue regeneration, the three key problems may hinder their clinical translations.…”