Biology subjects

Corridon, P. R.

Publications and source records attributed to Corridon, P. R..

6 recordsLinked to original sources

bioRxiv2022

Organ Scaffold Characterizations Using Intravital Microscopy

This study contains intravital microscopy (IVM) data to characterize organ scaffolds created using decellularization. Decellularization creates cell-free collagen-based matrices from native organs, which can be used as scaffolds for regenerative medicine applications. This data set contains in vivo assays evaluating the effectiveness of decellularization and structural and functional integrity of the acellular nephron in the post-transplantation environment. 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. 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). OIF formatted files illustrate IVM measurement processes and are made publicly available in a data repository. Such data is intended to support scientific reproducibility, complement future renal studies, and extend the use of this powerful imaging application to analyze other organ scaffold systems. O_TBL View this table: org.highwire.dtl.DTLVardef@4937b8org.highwire.dtl.DTLVardef@e91b6forg.highwire.dtl.DTLVardef@83eeforg.highwire.dtl.DTLVardef@15be0d4org.highwire.dtl.DTLVardef@105a2e5_HPS_FORMAT_FIGEXP M_TBL C_TBL Machine-accessible metadata file describing the reported data: https://doi.org/10.6084/m9.figshare.18703949.

bioengineering↗

bioRxiv2021

Analysis of vascular architecture and parenchymal damage generated by reduced blood perfusion in decellularized porcine kidneys using a gray level co-occurrence matrix

There is no cure for kidney failure, but a bioartificial kidney may help address this global problem. Decellularization provides a promising platform to generate transplantable organs. However, maintaining a viable vasculature is a significant challenge to this technology. Even though angiography offers a valuable way to assess scaffold structure/function, subtle changes are overlooked by specialists. In recent years, innovative image analysis methods in radiology have been suggested to detect and identify subtle changes in tissue architecture. The aim of our research was to apply one of these methods based on a gray level co-occurrence matrix (GLCM) computational algorithm in the analysis of vascular architecture and parenchymal damage generated by hypoperfusion in decellularized porcine. Perfusion decellularization of the whole porcine kidneys was performed using previously established protocols. We analyzed and compared angiograms of kidneys subjected to pathophysiological arterial perfusion of whole blood. For regions of interest (ROIs) covering kidney medulla and the main elements of the vascular network, five major GLCM features were calculated: angular second moment as an indicator of textural uniformity, inverse difference moment as an indicator of textural homogeneity, GLCM contrast, GLCM correlation, and sum variance of the co-occurrence matrix. In addition to GLCM, we also performed discrete wavelet transform analysis of angiogram ROIs by calculating the respective wavelet coefficient energies using high and low-pass filtering. We report statistically significant changes in GLCM and wavelet features, including the reduction of the angular second moment and inverse difference moment, indicating a substantial rise in angiogram textural heterogeneity. Our findings suggest that the GLCM method can be successfully used as an addition to conventional fluoroscopic angiography analyses of micro/macrovascular integrity following in vitro blood perfusion to investigate scaffold integrity. This approach is the first step toward developing an automated network that can detect changes in the decellularized vasculature.

bioengineering↗

bioRxiv2021

Assessing the Live Decellularized Renal Microvasculature Post-Transplantation using Intravital Microscopy

Transplantation is the ideal solution for end-stage renal failure, but the growing mismatch between organ supply and demand accentuates the need for alternative solutions like the bioartificial kidney. Several approaches to developing this technology have been demonstrated, and whole organ decellularization appears to be a promising methodology. One major challenge to this strategy is maintaining vascular integrity and functionality post-transplantation. Most models to examine the microvasculature have primarily utilized in vitro or in vivo techniques that are incapable of providing adequate spatial and temporal resolution. Here, we show that decellularized scaffolds orthotopically transplanted into rats initially retain microvascular structure in vivo using intravital two-photon microscopy, as previously identified in vitro. Large molecular weight dextran molecules also provide real-time evidence of the onset of ischemia and increases in microvascular permeability, support substantial translocation of dextran macromolecules from glomerular and peritubular capillary tracks as early as 12 hours after transplantation. Macromolecular extravasation continued across a week, at which time the decellularized microarchitecture was significantly compromised. These results indicate that a in vivo method capable of tracking microvascular integrity represents a powerful interdisciplinary approach for studying scaffold viability and identifying ways to promote scaffold longevity and angiogenesis in bioartificial organs.

bioengineering↗

bioRxiv2021

Intravital imaging of real-time endogenous actin dysregulation in proximal and distal tubules at the onset of severe ischemia-reperfusion injury

Severe renal ischemia-reperfusion injury (IRI) can lead to acute and chronic kidney dysfunction. Cytoskeletal modifications are among the main effects of this condition. The majority of studies that have contributed to the current understanding of IRI have relied on histological analyses using exogenous probes after the fact. Here we report the successful real-time visualization of actin cytoskeletal alterations in live proximal and distal tubules that arise at the onset of severe IRI. To achieve this, we induced fluorescent actin expression in these segments in rats with hydrodynamic gene delivery (HGD). Using intravital two-photon microscopy we then tracked and quantified endogenous actin dysregulation that occurred by subjecting these animals to 60 minutes of bilateral renal ischemia. Rapid (by 1-hour post-reperfusion) and significant (up to 50%) declines in actin content were observed. The decline in fluorescence within proximal tubules was significantly greater than that observed in distal tubules. Actin-based fluorescence was not recovered during the measurement period extending 24 hours post-reperfusion. Such injury decimated the renal architecture, in particular, actin brush borders, and hampered the reabsorptive and filtrative capacities of these tubular compartments. Thus, for the first time, we show that the combination of HGD and intravital microscopy can serve as an experimental tool to better understand how IRI modifies the cytoskeleton in vivo and provide an extension to current histopathological techniques.

physiology↗

bioRxiv2021

Modeling changes in vascular and extracellular matrix integrity that can occur in decellularized kidneys after implantation

A method was established to identify alterations in vascular patency and extracellular matrix integrity of decellularized porcine kidney scaffolds. These scaffolds were perfused with blood at physiologically normal (500 and 650 ml/min) and abnormal (200 ml/min) rates. Variations in venous outflow were then assessed over 24 hours. Angiographic data confirmed that standard arterial branching patterns and the integrity of the extracellular matrix were considerably disrupted. Scaffolds subjected to normal arterial perfusion rates observed drops in venous outflow across the 24 hours. These reductions rose from roughly 40% after 12 hours to 60% after 24 hours. At the end of the test period, regardless of the underlying damage that occurred, the kidneys appeared intact on the surface, and there were no apparent signs of clotting. In comparison, venous flow rates decreased by 80 to 100% across the 24 hours in acellular scaffolds subjected to a far lower perfusion rate of 200 ml/min. These kidneys also appeared intact after 24 hours of perfusion, but presented several arterial, venous, and ureteral clots. The results of this study provide insight into circumstances that limit scaffold viability and provide a simplified model to analyze other conditions that can better prepare scaffolds for long-term transplantation.

bioengineering↗

bioRxiv2021

Intravital microscopy confirmed microvascular and ECM preservation in the decellularized rat kidney directly after transplantation

Organ decellularization creates cell-free, collagen-based extracellular matrices that can be used as scaffolds for tissue engineering applications. This technique has recently gained much attention, yet adequate scaffold repopulation and implantation remain a challenge. Specifically, there still needs to be a greater understanding of scaffold responses post-transplantation and ways we can improve scaffold durability to withstand the in vivo environment. Recent studies have outlined vascular events that limit organ decellularization/recellularization scaffold viability for long-term transplantation. However, these insights have relied on in vitro/in vivo approaches that need enhanced spatial and temporal resolutions to investigate such issues at the microvascular level. This study uses intravital microscopy to gain instant feedback on their structure, function, and deformation dynamics. Thus, the objective of this study was to capture the effects of in vivo blood flow on the decellularized glomerulus, peritubular capillaries, and tubules after autologous and allogeneic orthotopic transplantation into rats. Large molecular weight dextran molecules label the vasculature. They revealed substantial degrees of translocation from glomerular and peritubular capillary tracks to the decellularized tubular epithelium and lumen as early as 12 hours after transplantation, providing real-time evidence of the increases in microvascular permeability. Macromolecular extravasation persisted for a week, during which the decellularized microarchitecture was significantly and comparably compromised and thrombosed in both autologous and allogeneic approaches. These results indicate that in vivo multiphoton microscopy is a powerful approach for studying scaffold viability and identifying ways to promote scaffold longevity and vasculogenesis in bioartificial organs.

physiology↗