Optically Transparent Anionic Nanofibrillar Cellulose Is Cytocompatible with Human Adipose Tissue-Derived Stem Cells and Allows Simple Imaging in 3D

Abstract

The anti-inflammatory and immunomodulatory properties of human mesenchymal stromal cells (MSCs) are a focus within regenerative medicine. However, 2D cultivation of MSCs for extended periods results in abnormal cell polarity, chromosomal changes, reduction in viability, and altered differentiation potential. As an alternative, various 3D hydrogels have been developed which mimic the endogenous niche of MSCs. Nevertheless, imaging cells embedded within 3D hydrogels often suffers from low signal-to-noise ratios which can be at least partly attributed to the high light absorbance and light scattering of the hydrogels in the visible light spectrum. In this study, human adipose tissue-derived MSCs (ADSCs) are cultivated within an anionic nanofibrillar cellulose (aNFC) hydrogel. It is demonstrated that aNFC forms nanofibres arranged as a porous network with low light absorbance in the visible spectrum. Moreover, it is shown that aNFC is cytocompatible, allowing for MSC proliferation, maintaining cell viability and multilineage differentiation potential. Finally, aNFC is compatible with scanning electron microscopy (SEM) and light microscopy including the application of conventional dyes, fluorescent probes, indirect immunocytochemistry, and calcium imaging. Overall, the results indicate that aNFC represents a promising 3D material for the expansion of MSCs whilst allowing detailed examination of cell morphology and cellular behaviour.

Electrical Stimulation of Adipose-Derived Stem Cells in 3D Nanofibrillar Cellulose Increases Their Osteogenic Potential

“…aNFC (GrowDexT ® ) was kindly provided by UPM Biochemicals, Helsinki, Finland. The handling and preparation of the 0.2% aNFC hydrogel was performed as previously described [ 44 ].…”

“…In our previous studies, we showed that hydrogels based on plant-derived nanofibrillar cellulose (NFC) [ 43 ] as well as aNFC hydrogels represent suitable scaffolds for the expansion and osteogenic differentiation of ASCs in 3D [ 44 ]. Briefly, we demonstrated that NFC does not negatively affect proliferation of ASCs [ 43 ], whilst aNFC significantly increases their viability compared to 2D controls [ 44 ].…”

Impact of 3D cell culture on bone regeneration potential of mesenchymal stromal cells

“…To address these problems, MSCs have been subjected to a wide range of 3D cell culture methods including cultivation as scaffold-free spheroids [ 62 , 63 ] (reviewed in [ 64 ]) and different hydrogel scaffolds including alginates [ 65 ], collagen [ 66 ], Matrigel [ 67 ] and various formulations of cellulose [ 68 – 71 ].…”

“…In our hands, low concentrations (0.2%) of nanofibrillar cellulose did not negatively affect the proliferation of BM-MSCs, AD-MSCs and palatal MSCs, whereas higher concentrations (0.5%) significantly reduced cellular viability and proliferation compared to 2D controls [ 70 ]. In contrast, a follow-up study showed that an anionic form of nanofibrillar cellulose significantly increased the viability of human AD-MSCs [ 71 ]. Similarly, Yin and colleagues recently reported that 3D cultivation of AD-MSCs in a nanofibrous polysaccharide hydrogel increases their proliferation and viability [ 88 ].…”

“…In addition, 2D micropores of 60 and 550 μm have been reported to have a positive impact on osteogenic differentiation [ 127 ]. Interestingly, electron microscopic analyses of the structure of various hydrogels including different forms of nanofibrillar cellulose and fibrin have revealed a presence both nano- and micropores [ 70 , 71 , 128 ]. Thus, these nanoscopic and microscopic features could provide a potential explanation for the increased osteogenic potential of MSCs in 3D.…”