Generation of co-culture spheroids as vascularisation units for bone tissue engineering

Abstract

Cell spheroids represent attractive building units for bone tissue engineering, because they provide a threedimensional environment with intensive direct cellcell contacts. Moreover, they allow for co-culture of both osteoblasts and vessel-forming cells, which may markedly increase their survival and vascularisation after transplantation. To test this hypothesis, we generated coculture spheroids by aggregating different combinations of primary human osteoblasts (HOB), human dermal microvascular endothelial cells (HDMEC) and normal human dermal fibroblasts (NHDF) using the liquid overlay technique. Mono-culture spheroids consisting either of HOB or HDMEC served as controls. After in vitro characterisation, the different spheroids were transplanted into dorsal skinfold chambers of CD1 nu/nu mice to study in vivo their viability and vascularisation over a 2-week observation period by means of repetitive intravital fluorescence microscopy and immunohistochemistry. In vitro, co-culture spheroids containing HDMEC rapidly formed dense tubular vessel-like networks within 72 h and exhibited a significantly decreased rate of apoptotic cell death when compared to mono-culture HDMEC spheroids. After transplantation, these networks interconnected to the host microvasculature by external inosculation. Of interest, this process was most pronounced in HOB-HDMEC spheroids and could not further be improved by the addition of NHDF. Accordingly, HOB-HDMEC spheroids were larger when compared to the other spheroid types. These findings indicate that HOB-HDMEC spheroids exhibit excellent properties to preserve viability and to promote proliferation and vascularisation. Therefore, they may be used as functional vascularisation units in bone tissue engineering for the seeding of scaffolds or for the vitalisation of non-healing large bone defects.

Cell‐based strategies for vascular regeneration

“…Various scaffolds coated with ECs and OBs showed the expression of angiogenic genes, and the formation of vessel‐like structures in vitro . 52 In vivo studies demonstrated that co‐culture systems promoted the formation of vascularized bone tissue, and the vessel‐like network in scaffolds anastomosed well with the host vasculature . In addition, many research groups have studied the co‐culture system of ECs and MSCs.…”

Cell surface engineering with polyelectrolyte-stabilized magnetic nanoparticles: A facile approach for fabrication of artificial multicellular tissue-mimicking clusters

“…Multicellular spheroids are cultivated as 3D-cell culture models employed in cancer research [37][38][39] and pharmaceutical screening [40,41]; in addition, applications of spheroids as building blocks in tissue engineering have been envisaged [36,[42][43][44]. Thus, rendering multicellular spheroids with magnetic functionality is deemed important for assembly of artificial tissues, and magnetic nanoparticles have been introduced into cells prior to fabrication of spheroids [9].…”

Evaluation of the shape, viability, stemness and osteogenic differentiation of cell spheroids formed from human gingiva-derived stem cells and osteoprecursor cells

“…The results of the present study demonstrated that cell spheroids formed from a single or two cell types preserved viability and may have promoted proliferation in the three-dimensional environment. Previous reports have indicated that co-culture spheroids generated by aggregating different combinations of primary human osteoblasts and human dermal microvascular endothelial cells exhibit excellent properties of preserving viability and promoting proliferation and vascularization (26). It may be suggested that the co-culture technique may be used to generate functional units for tissue-engineering purposes.…”