Overcoming physical constraints in bone engineering: ‘the importance of being vascularized’

Abstract

Bone plays several physiological functions and is the second most commonly transplanted tissue after blood. Since the treatment of large bone defects is still unsatisfactory, researchers have endeavoured to obtain scaffolds able to release growth and differentiation factors for mesenchimal stem cells, osteoblasts and endothelial cells in order to obtain faster mineralization and prompt a reliable vascularization.Nowadays, the application of osteoblastic cultures spans from cell physiology and pharmacology to cytocompatibility measurement and osteogenic potential evaluation of novel biomaterials. To overcome the simple traditional monocultures in vitro, co-cultures of osteogenic and vasculogenic precursors were introduced with very interesting results. Increasingly complex culture systems have been developed, where cells are seeded on proper scaffolds and stimulated so as to mimic the physiological conditions more accurately. These bioreactors aim at enabling bone regeneration by incorporating different cells types into bioinspired materials within a surveilled habitat.This review is focused on the most recent developments in the organomimetic cultures of osteoblasts and vascular endothelial cells for bone tissue engineering.

Cytokine, Chemokine, and Growth Factor Profile Characterization of Undifferentiated and Osteoinduced Human Adipose-Derived Stem Cells

“…A possible approach might consist in elucidating the behavior of ASCs in coculture systems, with endothelial cells that are known to be key players in bone formation and regeneration [5]. …”

“…In addition, inborn malformations, alveolar resorption, and critical-size bone defects resulting from severe trauma or malignant tumor resection [3] make bone the second most transplanted tissue after blood [4]. Treatments include grafting with both autogenous and allogenic bone, which are not without limitations [5]. …”

Increased differentiation and production of extracellular matrix components of primary human osteoblasts after cocultivation with endothelial cells: A quantitative proteomics approach

“…However, these cells are rather representative of microvasculature, whereas primary microvascular endothelial cells (eg from human dermis) are also commercially available and might be more representative for simulating conditions after implantation of tissue blocks in vivo. 47,48 Experiments with different types of ECs are warranted.…”

Metronidazole-functionalized iron oxide nanoparticles for molecular detection of hypoxic tissues

“…For instance, the cell viability inside tridimensional tissue-like constructs for regenerative medicine is strongly dependent on the oxygenation level, since the diffusion of oxygen and nutrients to cells from capillary networks does not exceed 100-200 μm. 18 Because the low pressure of oxygen represents a marked feature of pathological tissues, the conjugation of bioreductive compounds to molecular probes has been extensively exploited to detect and reach hypoxic cells. 19 Bioreductive molecules are selectively reduced in hypoxic tissues, generating reactive intermediates that bind to intracellular molecules.…”