Failure to Restore
" Myocardial Infarction/Apoptosis
Edelberg et al. (2002)
Restoration of Engraftment
Xaymardan et al. (2004b)
mice. This tissue is engrafted into the 5 x 3 mm subcutaneous pocket, and gentle pressure is applied with the tips of the forceps to express air from the pocket and facilitate the adherence between donor and recipient tissues. Engraftment viability is scored 7 d post transplantation via tissue integrity, electrocardiographic (ECG) activity, and blood flow.
To measure the effects of specific angiogenic pathways, the host transplantation site can be treated with molecular, protein, or cellular combinations. Specifically, the murine pinnae can be treated with up to 20 ^l of injective either before or at the time of allograft transplantation (through a 30 G x 8 mm needle injected subdermally). In addition, the effects of remote treatments such as contralateral injections or systematic manipulations, including bone marrow transplantation, can be tested in this model.
Assessment protocols The host ears are grossly analyzed 7 d post transplantation for viability. One qualitative method used to assess viability is transplant integrity. Ears that exhibit intact, healthy tissue are scored as viable, whereas any signs of tissue degradation, inflammation, or necrosis are scored as nonviable (see Figure 78.1).
Local ECGs can be employed to confirm cardiac allograft viability. Specifically, ECGs are acquired via pinnal electrodes to measure allograft activity with 500 Hz sampling, band pass filtered between 3.0 and 100 Hz, and notch filtered at 60.0 Hz, amplified 1000 x. Limb electrodes are placed to record the endogenous heart simultaneously to control for field effect.
Functional blood flow to the transplanted cardiac tissue can also be assessed by laser Doppler with an
Advance Laser Flowmeter ALF21/2D (Advance, Tokyo) as previously described (Edelberg et al., 2002a). Blood flow measurements are taken at baseline (day 0) and 7 d post transplantation to assess angiogenic activity.
The physiological significance of these findings in the cardiac allograft model requires confirmation in the endogenous heart. To directly assess the role of various genes/pathways in angiogenesis in the intact heart, murine and rat models provide select advantages and limitations. Specifically, for strategies targeting the wild-type heart, studies employing rats, which have less variability in coronary anatomy as compared with mice, provide a more quantitative model for subsequent myocardial infarction studies. Murine models can provide a more qualitative model in myocardial infarction studies by allowing the use of transgenic animals. Notably, the hearts of both species can be targeted selectively in open interventions to assess the impact of molecular and cellular approaches to alter cardiac angiogenesis.
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