Cover Picture: Biomineralized Polysaccharide Capsules for Encapsulation, Organization, and Delivery of Human Cell Types and Growth Factors (Adv. Funct. Mater. 6/2005)

Abstract

The cover shows biomineralized polysaccharide capsules with specifiable make‐up, which can provide microenvironments for stabilization, growth, and differentiation of human cell types, as reported by Oreffo and co‐workers on p. 917. The capsules are amenable to complexation with a range of bioactive molecules and cells, offering tremendous potential as multifunctional scaffolds and delivery vehicles in tissue regeneration of hard and soft tissues. The construction of biomimetic microenvironments with specific chemical and physical cues for the organization and modulation of a variety of cell populations is of key importance in tissue engineering. We show that a range of human cell types, including promyoblasts, chondrocytes, adipocytes, adenovirally transduced osteoprogenitors, immunoselected mesenchymal stem cells, and the osteogenic factor, rhBMP‐2 (BMP: bone morphogenic protein), can be successfully encapsulated within mineralized polysaccharide capsules without loss of function in vivo. By controlling the extent of mineralization within the alginate/chitosan shell membrane, degradation of the shell wall and release of cells or rhBMP‐2 into the surrounding medium can be regulated. In addition, we describe for the first time the ability to generate bead‐in‐bead capsules consisting of spatially separated cell populations and temporally separated biomolecule release, entrapped within alginate/chitosan shells of variable thickness, mineralization, and stability. Such materials offer significant potential as multifunctional scaffolds and delivery vehicles in tissue regeneration of hard and soft tissues.

Hybrid Cellular−Inorganic Core−Shell Microparticles: Encapsulation of Individual Living Cells in Calcium Carbonate Microshells

“…6,16,17,[20][21][22][23][24][25] Recently, large populations of human cells were encapsulated in mineralized polysaccharide millimeter-sized capsules in order to produce multifunctional scaffolds and delivery vehicles in tissue engineering. 26 The current paper shows that at the early stages of CaCO 3 precipitation individual cells act as nucleation sites and are completely and uniformly coated with the CaCO 3 micrometer-thick layer. Such hybrid microparticles can be easily fabricated and, as long as they combine the properties of CaCO 3 and living cells, can be used in a number of practical applications.…”

“…We suppose that the formation of such hybrid core−shell microparticles is facilitated not only by yeast cells but by other microorganisms as well. Some previous reports describe the formation of biogenic CaCO 3 in the presence of various microorganisms; however, most likely due to the long incubation times (generally exceeding several days), the authors of these reports observed only relatively large microcrystals presumably produced in the presence of cells and no individual encapsulated cells were found. ,,,− Recently, large populations of human cells were encapsulated in mineralized polysaccharide millimeter-sized capsules in order to produce multifunctional scaffolds and delivery vehicles in tissue engineering . The current paper shows that at the early stages of CaCO 3 precipitation individual cells act as nucleation sites and are completely and uniformly coated with the CaCO 3 micrometer-thick layer.…”

Selective Coprecipitation of Polyphenols in Bioactive/Inorganic Complexes

“…Green at al. 39 described the encapsulation of various human cell types and growth factors in alginate/chitosan microcapsules mineralized with calcium phosphate and showed that the degree of mineralization of the polysaccharide microcapsules determined the delivery of the cells at the targeted site. Xu et al 40 produced stable amorphous calcium carbonate microparticles stabilized by phytic acid.…”

“…Butler et al investigated the crystallization of calcium carbonate in the presence of various gelling and nongelling biopolymers. Green at al . described the encapsulation of various human cell types and growth factors in alginate/chitosan microcapsules mineralized with calcium phosphate and showed that the degree of mineralization of the polysaccharide microcapsules determined the delivery of the cells at the targeted site.…”