"Introduction: Decellularization creates cell-free collagen-based extracellular matrices from native organs, which can be used as scaffolds for regenerative medicine applications1-8. This technique has gained much attention in recent times. However, there is still a limited understanding of scaffold responses in vivo post-transplantation and ways we can improve scaffold durability to withstand the in vivo environment9. This study uses intravital microscopy (IVM) to gain instant feedback on their structure, function, and deformation dynamics.
Methodology: In vivo assays were developed to evaluate the effectiveness of decellularization and structural and functional integrity of the acellular nephron in the post-transplantation environment. Cohorts of 2-3-month-old male Sprague Dawley rats were used: non-transplanted (n = 4), transplanted day 0 (n = 4), transplanted day 1 (n = 4), transplanted day 2 (n = 4), and transplanted day 7 (n = 4). Qualitative and quantitative assessments of scaffold DNA concentrations, tissue fluorescence signals, structural and functional integrities of various decellularized nephron segments, and velocity within the microcirculation were acquired and compared to the native (non-transplanted) organ.
Results: Large molecular weight dextrans, which lined the vasculature, provided real-time evidence of ischemia onset and microvascular permeability increases. We observed substantial translocation of macromolecules from glomerular/peritubular capillary tracks as early as 12 hours post-transplantation. Blood extravasation continued across a week. During that time, the decellularized microarchitecture was significantly compromised and thrombosed.
Conclusions: Models examining the microvasculature primarily utilize in vitro/in vivo techniques that cannot provide adequate spatial/temporal resolution. These results identifies IVM as a powerful approach for studying scaffold viability and identifying ways to promote scaffold longevity, and angiogenesis in bioartificial organs. We also created the basis to develop a fractal model that can be used to explore ways to improve scaffold integrity to support recellularization and withstand deformation in transplantation environments.
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