Semipermeable Capsules Wrapping a Multifunctional and Self-regulated Co-culture Microenvironment for Osteogenic Differentiation

Abstract

A new concept of semipermeable reservoirs containing co-cultures of cells and supporting microparticles is presented, inspired by the multi-phenotypic cellular environment of bone. Based on the deconstruction of the “stem cell niche”, the developed capsules are designed to drive a self-regulated osteogenesis. PLLA microparticles functionalized with collagen I, and a co-culture of adipose stem (ASCs) and endothelial (ECs) cells are immobilized in spherical liquified capsules. The capsules are coated with multilayers of poly(L-lysine), alginate, and chitosan nano-assembled through layer-by-layer. Capsules encapsulating ASCs alone or in a co-culture with ECs are cultured in endothelial medium with or without osteogenic differentiation factors. Results show that osteogenesis is enhanced by the co-encapsulation, which occurs even in the absence of differentiation factors. These findings are supported by an increased ALP activity and matrix mineralization, osteopontin detection, and the up regulation of BMP-2, RUNX2 and BSP. The liquified co-capsules also act as a VEGF and BMP-2 cytokines release system. The proposed liquified capsules might be a valuable injectable self-regulated system for bone regeneration employing highly translational cell sources.

In vivo osteogenic differentiation of stem cells inside compartmentalized capsules loaded with co-cultured endothelial cells

“…Poly(L-lactic acid) microparticles (µPLLAs) were produced by an oil/water (o/w) emulsion technique and surface modified with collagen I after plasma treatment as similarly described in our previous reports [27][28][29][30]. Briefly, PLLA (5% w/v, Mw~1,600-2,400, 70% crystallinity, Polysciences) was dissolved in methylene chloride (CH 2 Cl 2 , Fisher Chemical).…”

2.11 Polymers of Biological Origin ☆

“…Bearing this in mind, researchers have been started to encapsulate viable and functional cells into 3D environments that mimic the natural ECM. 155 Several methods have been used to encapsulate cells in 3D structures, from simple gravitational dripping to more complex ones as microtechnologies 156 or additive manufacturing. 157 This strategy has been shown interesting and promising results for different applications such as, (i) cell immunoisolation and drug delivery; 158 (ii) storage and transport; 159 and (iii) cell delivery.…”

Design of spherically structured 3D in vitro tumor models -Advances and prospects

“…To overcome these limitations, various studies have attempted to include ECM mimetics in the form of spherically structured scaffolds, namely microparticles or microcapsules. These technologies have been extensively used in the field of tissue engineering and stem cell research [16][17][18], and offer further opportunities to mimic the complexity of the TME in vitro. In fact, this approach opens the possibility to study biochemical and tumor-ECM dependent mechanical cues through the inclusion of modular matrix-mimetic scaffolds [19].…”