Robert Brenes2, Caroline C. Jadlowiec1, Mackenzie Bear1, Peter Hashim1, Clinton D. Protack1, Xin Li1, Wei Lv1, Michael J. Collins1, Alan Dardik1
1Interdepartmental Program in Vascular Biology and Therapeutics, Yale University School of Medicine, New Haven, CT; 2Saint Mary's Hospital, The Stanley J. Dudrick Department of Surgery, Waterbury, CT.
OBJECTIVES: Clinical trials currently evaluating stem cell therapy for patients with critical limb ischemia are conducted with different protocols, including use of different stem cell populations and different injection protocols, providing little means to compare trials and guide therapy. Accordingly, we developed a murine model of severe ischemia to allow methodical testing of relevant clinical parameters.
METHODS: High femoral artery ligation and total excision of the superficial femoral artery was performed on C57BL/6 mice. MNC were isolated from the bone marrow of donor mice and injected into the semimembranosus or gastrocnemius muscle. Vascular and functional outcomes were measured using invasive Doppler, laser Doppler perfusion imaging, and the Tarlov and ischemia scores. Histological analysis included quantification of muscle fiber area and number as well as capillary density.
RESULTS: Blood flow and functional outcomes were improved in MNC-treated mice as compared to controls over a 4-week time course (Flow: p<0001; Tarlov: p=.0004; ischemia score: p=.0002). MNC-treated mice also showed greater gastrocnemius fiber area (p=.0053) and increased capillary density (p=.0004). Dose-response analysis showed increased angiogenesis and gastrocnemius fiber area but no changes in macroscopic vascular flow or functional scores. Mice injected proximally to the ischemic area had overall similar functional outcomes to mice injected more distally, but increased muscle flow, capillary density, and gastrocnemius fiber area (p<.05).
CONCLUSIONS: Our severe ischemia model is reliable and shows a response to MNC treatment for both functional and vascular outcomes. A dose response to MNC injection appears to be present suggesting that an optimal cell number for stem cell therapy exists and that preclinical testing needs to be performed to optimally guide human trials. Injection of MNC proximal to the site of ischemia may provide some different outcomes and warrants additional study.
AUTHOR DISCLOSURES: M. Bear, Nothing to disclose; R. Brenes, Nothing to disclose; M. J. Collins, Nothing to disclose; A. Dardik, Nothing to disclose; P. Hashim, Nothing to disclose; C. C. Jadlowiec, Nothing to disclose; X. Li, Nothing to disclose; W. Lv, Nothing to disclose; C. D. Protack, Nothing to disclose.
|
BARE-METAL STENTS
(n=164 pts/197 vessels) |
COVERED STENTS
(n=61 pts/ 67 vessels) |
p-Value |
|
%±SD* |
|
PRIMARY INTERVENTION GROUP |
n=149 pts/181 vessels |
n=42 pts/45 vessels |
|
Freedom from restenosis |
53±4 |
92±6 |
.003 |
Freedom from recurrence |
58±4 |
95±5 |
0.001 |
Freedom from re-intervention |
59±5 |
95±5 |
0.001 |
Primary patency |
60±5 |
91±6 |
0.003 |
Secondary patency |
95±2 |
100 |
0.46 |
RE-INTERVENTION GROUP |
n=15 pts/16 vessels |
21 pts/22 vessels |
|
Freedom from restenosis |
49±14 |
89±10 |
0.04 |
Freedom from recurrence |
44±14 |
89±10 |
0.001 |
Freedom from re-intervention |
56±12 |
89±10 |
0.03 |
Primary patency |
45±14 |
60±12 |
0.08 |
Secondary patency |
100 |
82±10 |
0.10 |
*2-year Kaplan-Meier estimates
Posted April 2012