12.2. Bone
Trauma or diseases may cause bone defects and bone substitute materials are used for repair and reconstruction. Conventional treatment approaches involve bone grafting, where bone from the patient (autograft) at another site (e.g. hips or ribs) are removed or bone from a human donor (allograft) are used to fill the defects. However, as this surgery has a high risk and the availability of bone grafts is limited, bone substitute materials have been developed based on ceramics, polymers and composites. More than 40
such bone substitute materials were commercially available 2009, including one injectable putty containing alginate, demineralised bone matrix and collagen.’ Relevant properties for such materials are biocompatibility, bioactivity (formation of strong biomaterial-bone interface), allowing osteointegration (direct structural and functional connection between living bone and implant), osteoconductivity (conducting bone formation on a surface or into pores of an implant), biodegradability and osteoinductivity
(promote or induce bone formation for example by differentiation of osteoprogenitor cells into bone forming osteoblasts).
Alginate systems have shown interesting results within bone regeneration when used as a as a delivery vehicle and/or to guide tissue repair providing a temporary extracellular matrix (ECM) for cells to infiltrate and migrate while depositing new bone tissue. The degradation rate of alginate hydrogels should preferably mirror the deposition of newly formed tissue. Alginate hydrogels with cells entrapped that were made from alginates of different molecular weights tuned by gamma irradiation, demonstrated regulated
bone formation via controlled scaffold degradation. Examples of other alginate systems providing signalling cues promoting osteogenesis in addition to scaffold degradation, includes controlled matrix rigidity for differentiation of stem cells, use of alginates with covalently bound cell attachment peptides and delivery of growth factors and genes. 52 53 79 100 157
12.2. BoneTrauma or diseases may cause bone defects and bone substitute materials are used for repair and reconstruction. Conventional treatment approaches involve bone grafting, where bone from the patient (autograft) at another site (e.g. hips or ribs) are removed or bone from a human donor (allograft) are used to fill the defects. However, as this surgery has a high risk and the availability of bone grafts is limited, bone substitute materials have been developed based on ceramics, polymers and composites. More than 40such bone substitute materials were commercially available 2009, including one injectable putty containing alginate, demineralised bone matrix and collagen.’ Relevant properties for such materials are biocompatibility, bioactivity (formation of strong biomaterial-bone interface), allowing osteointegration (direct structural and functional connection between living bone and implant), osteoconductivity (conducting bone formation on a surface or into pores of an implant), biodegradability and osteoinductivity(promote or induce bone formation for example by differentiation of osteoprogenitor cells into bone forming osteoblasts).Alginate systems have shown interesting results within bone regeneration when used as a as a delivery vehicle and/or to guide tissue repair providing a temporary extracellular matrix (ECM) for cells to infiltrate and migrate while depositing new bone tissue. The degradation rate of alginate hydrogels should preferably mirror the deposition of newly formed tissue. Alginate hydrogels with cells entrapped that were made from alginates of different molecular weights tuned by gamma irradiation, demonstrated regulatedbone formation via controlled scaffold degradation. Examples of other alginate systems providing signalling cues promoting osteogenesis in addition to scaffold degradation, includes controlled matrix rigidity for differentiation of stem cells, use of alginates with covalently bound cell attachment peptides and delivery of growth factors and genes. 52 53 79 100 157
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