Healthy bone tissue is a dynamic tissue subject to constant remodelling by bone-forming and bone-resorbing cells. Still, large bone defects as caused by diseases, trauma or tumor resection cannot be healed by the regenerative capacity of bone tissue. With the aid of synthetic biodegradable materials, however, this self-healing capacity can be expanded to these so-called critical-sized defects. Therefore, the long-term goal is of this line of research within the Department of Biomaterials is to develop an injectable, synthetic bone substitute that mimics the unique properties of native bone as close as possible.

Since bone tissue is best described as an organic/inorganic nanocomposite material (collagen matrix reinforced by calcium phosphate crystals), it is hypothesized that the optimal synthetic bone tissue-equivalent will also be comprised of polymeric and inorganic composite components. Within the Department of Biomaterials, two separate lines of research are being followed. First, injectable bone fillers with enhanced bone forming behavior have been developed based upon self-setting calcium phosphate cement matrices that are functionalized with degradable polymeric microspheres. The opposite approach is carried out by constructing biomimetic nanocomposites from injectable, flexible hydrogel matrices that are functionalized with mineral dispersions of CaP nanocrystals.

Bone-substituting composite consisting of injectable calcium phosphate cement matrix and degradable, polymeric (PLGA) microspheres.

Histology of an injectable, macroporous bone-substitute consisting of calcium phosphate cement matrix and rhBMP-2 containing, degradable polymeric (PLGA) microspheres after 12 weeks of implantation in cranial rat defects.

Key references:

1. Ruhe PQ, Boerman OC, Russel FG, Spauwen PH, Mikos AG, Jansen JA. Controlled release of rhBMP-2 loaded poly(dl-lactic-co-glycolic acid)/calcium phosphate cement composites in vivo.
   J Control Release 2005;106(1-2):162-71.
2. Jansen JA, Vehof JW, Ruhe PQ, Kroeze-Deutman H, Kuboki Y, Takita H, Hedberg EL, Mikos AG. Growth factor-loaded scaffolds for bone engineering. J Control Release 2005;101(1-3):127-36.