Extracorporeal Hypothermic Perfusion Device for Intestinal Graft Preservation to Decrease Ischemic Injury During Transportation.

INTRODUCTION: The small intestine is one of the most ischemia-sensitive organs used in transplantation. To better preserve the intestinal graft viability and decrease ischemia-reperfusion injury, a device for extracorporeal perfusion was developed. We present the results for the first series of perfused human intestine with an intestinal perfusion unit (IPU). METHODS: Five human intestines were procured for the protocol. (1) An experimental segment was perfused by the IPU delivering cold preservation solution to the vascular and luminal side continually at 4 ºC for 8 h. (2) Control (jejunum and ileum) segments were preserved in static cold preservation. Tissue samples were obtained for histopathologic grading according to the Park/Chiu scoring system (0 = normal, 8 = transmural infarction). RESULTS: Jejunal experimental segments scored 2.2 with the Park/Chiu system compared to the control segments, which averaged 3.2. Overall scoring for ileum experimental and control segments was equal with 1.6. CONCLUSION: This data presents proof of concept that extracorporeal intestinal perfusion is feasible. The evidence shows that the IPU can preserve the viability of human intestine, and histopathologic evaluation of perfused intestine is favorable. Our early results can eventually lead to expanding the possibilities of intestinal preservation.

A novel device to preserve intestinal tissue ex-vivo by cold peristaltic perfusion.

In the past two decades, much advancement has been made in the area of organ procurement and preservation for the transplant of kidneys, livers, and lungs. However, small intestine preservation remains unchanged. We propose a new preservation system for intestinal grafts that has the potential to increase the viability of the organ during transport. When experimented with porcine intestine, our device resulted in superior tissue quality than tissue in standard of care.

Maximizing fluorescence collection efficiency in multiphoton microscopy.

Understanding fluorescence propagation through a multiphoton microscope is of critical importance in designing high performance systems capable of deep tissue imaging. Optical models of a scattering tissue sample and the Olympus 20X 0.95NA microscope objective were used to simulate fluorescence propagation as a function of imaging depth for physiologically relevant scattering parameters. The spatio-angular distribution of fluorescence at the objective back aperture derived from these simulations was used to design a simple, maximally efficient post-objective fluorescence collection system. Monte Carlo simulations corroborated by data from experimental tissue phantoms demonstrate collection efficiency improvements of 50% - 90% over conventional, non-optimized fluorescence collection geometries at large imaging depths. Imaging performance was verified by imaging layer V neurons in mouse cortex to a depth of 850 µm.

Multiphoton microscopy of cleared mouse organs.

Typical imaging depths with multiphoton microscopy (MPM) are limited to less than 300 mum in many tissues due to light scattering. Optical clearing significantly reduces light scattering by replacing water in the organ tissue with a fluid having a similar index of refraction to that of proteins. We demonstrate MPM of intact, fixed, cleared mouse organs with penetration depths and fields of view in excess of 2 mm. MPM enables the creation of large 3-D data sets with flexibility in pixel format and ready access to intrinsic fluorescence and second-harmonic generation. We present high-resolution images and 3-D image stacks of the brain, small intestine, large intestine, kidney, lung, and testicle with image sizes as large as 4,096 x 4,096 pixels.