The main criterion in assessing the therapeutic efficacy of tissue engineered construct is the successful restoration of the host's physiology. Direct and non-invasive in vivo monitoring of a construct is of great importance for the following reasons: it provides correlations between construct function and physiologic effects post-implantation in vivo; and it offers the possibility of assessing changes in construct function that may be used to develop early markers of construct failure in advance of the end-point effects. The overall objective of the proposed research is to develop a noninvasive methodology to monitor in vivo the function of an implanted tissue engineered pancreatic substitute. NMR is uniquely suited to perform such studies since it is a non-invasive modality that has the ability to probe into the intracellular metabolism of the construct, and to view the anatomy of the host at the site of implantation. NMR spectroscopic and imaging techniques can monitor several intracellular and extracellular metabolites without necessitating the introduction of foreign agents or the fixation of cells. It is our hypothesis that NMR detectable metabolic indexes can be used to monitor the function of an implanted tissue engineered pancreatic substitute and provide early indicators of implant failure while the recipient is still euglycemic. The NMR nuclei examined in this study include 1H, 19F and 31P, while the model pancreatic construct utilized is composed of mouse insulinoma #TC-tet cells or mouse islets encapsulated in alginate/poly-L- lysine/alginate beads and contained within an agarose matrix that allows for easy retrieval. The following Specific Aims are designed to address our hypothesis:
Specific Aim 1 : To optimize in vivo NMR signal acquisition with inductively coupled RF-coils.
Specific Aim 2 : To develop and validate a model of time-dependent oxygen and cell density gradients within constructs.
Specific Aim 3 : To non-invasively assess the function of an implanted tissue engineered pancreatic substitute and correlate that to end point physiologic events. We believe this to be a thorough, quantitative and a significant study to monitor the function of an implanted tissue engineered substitute that will identify metabolic events associated with failure ahead of its end physiologic effect. Proposed experiments are founded on strong preliminary data and we are confident that they will pave the way for further imaging studies in tissue engineering. ? ? ?
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