Autologous stem cells for functional myocardial repair

Stem cell homing and angiomyogenesis in transplanted hearts are enhanced by combined intramyocardial SDF-1alpha delivery and endogenous cytokine signaling

We used a heterotopic transplanted working heart model to probe the collaborative role of bone marrow-derived progenitor cells (BPCs) and stromal cell-derived factor (SDF)-1alpha in attenuating tissue remodeling in recipient and transplanted hearts. BPCs from male transgenic rats expressing green fluorescent protein (GFP(+) BPCs, 2 x 10(6) cells) were injected intravenously into myeloablated female rats. One month later, heterotopic heart transplantation was performed. The left anterior descending coronary artery (LAD) of the recipient heart was occluded permanently. Mesenchymal stem cells (MSCs; 2 x 10(6) cells) with a null gene (null group) or overexpressing SDF-1alpha (SDF-1alpha group) were injected intramyocardially in the LAD perfusion region of both recipient and transplanted hearts. Recipient and transplanted hearts (n = 10 hearts/group) were harvested 21 days later for analysis. The survival of transplanted hearts was assessed daily by palpation in additional animals (n = 7). Five days after LAD occlusion, subpopulations of GFP(+) BPCs in the circulation were significantly higher in the SDF-1alpha group. Y chromosome, 5-bromo-2'-deoxyuridine, Ki67-positive nuclei, newly formed vessels, and GFP(+) cells significantly increased in transplanted hearts of the SDF-1alpha group at 21 days after the injection of MSCs overexpressing SDF-1alpha, whereas fewer TUNEL-positive nuclei were found. The survival of transplanted hearts was also markedly increased in the SDF-1alpha group (P < 0.05). Supplementation of endogenous cytokines released from the ischemic myocardium with exogenous MSCs overexpressing SDF-1alpha significantly increased BPC homing to acutely ischemic recipient and progressively ischemic transplanted hearts. BPC recruitment resulted in the regeneration of new cardiomyocytes and blood vessels and extended survival of the transplanted hearts.

Effects of autologous stem cells on immunohistochemical patterns and gene expression of metalloproteinases and their tissue inhibitors in doxorubicin cardiomyopathy in a rabbit model

This study aims to investigate the expression of metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) in chronic doxorubicin cardiomyopathy in a rabbit model and to evaluate the effects of bone marrow-derived mesenchymal stem cell (MSC) transplantation in this disease. Thirty-nine 3-month-old New Zealand rabbits were divided into 4 groups: group 1 (n = 9) was the untreated control. Groups 2-4 were treated with 6 weeks of doxorubicin (3 mg/kg). Group 2 (n = 6) received no further treatment. In group 3 (n = 9), animals were treated with culture medium (CM) alone. In group 4 (n = 15), autologous MSCs (1.5-2.0 x 10(6)/ml) were injected in the left ventricular (LV) wall. Hearts were stained with HE and picrosirius red. MMP-1, -2, -3 and -9 and TIMP-2 and -3 were detected immunohistochemically. The mRNA levels were determined by real-time polymerase chain reaction. The results confirmed that doxorubicin treatment resulted in minimal myocardial fibrosis and showed that expression of MMPs increased and TIMP-3 decreased. The injection procedure resulted in increased myocardial fibrosis in groups 3 and 4. After MSC injection, MMP-1, MMP-2, and TIMP-3 expression was higher than that in group 2. CM injection led to more fibrosis, elevated TIMP-3, but diminished MMP-1 and MMP-2 expression compared with MSC injection. The mRNA levels of MMPs and TIMPs were not significantly different among all groups. In conclusion, chronic doxorubicin cardiomyopathy was characterized by increased MMP and decreased TIMP-3 expression. MSCs injection into the LV resulted in marked differences of collagen content and MMP/TIMP expression in the whole heart, although significant numbers of living MSCs were not detected after 4 weeks.

Autologous bone marrow-derived progenitor cell myocardial delivery for recent myocardial infarction patients following early angioplasty: results from a pilot study

PURPOSE

Cellular cardiomyoplasty is a potential therapeutic approach to preventing left ventricular remodeling after myocardial infarction and has shown encouraging results such as induction of neoangiogenesis and functional improvement of diseased hearts. We report the results of a pilot study on progenitor cells in five patients with acute myocardial infarction (AMI).

MATERIALS AND METHODS

Patients with single-vessel disease who had their first episode of myocardial infarction and underwent angioplasty after 48 h (an average of 17 days following myocardial infarction) were included in the study. Mononuclear cells (MNCs) (1x10(7)) were isolated by Ficoll Hypaque method from 60 ml of bone marrow (BM) obtained from the iliac crest of 5 patients (aspiration was performed under local anesthesia). The mean CD34 count was 1-4%. After confirming the patency of the affected vessel postangioplasty, cellular concentrate was injected into the affected artery in 3-ml boluses (three to four injections), with intermittent occlusion.

RESULTS

The mean age of all five male patients was 48.6+13.7 years. At 1 year, five patients were asymptomatic, and one had Class II dyspnea on exertion. The results of an echocardiogram performed at 6 months showed an improvement in ejection fraction (EF) from 35.3% to 43.13% and in fractional shortening from 24.75% to 28.33%. End-systolic volume decreased from 115.5 to 92.3 ml, end-diastolic volume decreased from 177.5 to 170 ml, and end-systolic dimensions also decreased from 4.26 to 4 mm, demonstrating positive left ventricular remodeling. Repeat echocardiogram at 1 year showed persistent improvement in EF. No adverse events were noted either before or after the procedure.

CONCLUSION

The injection of autologous BM MNCs is a safe and efficacious therapy following early revascularization in AMI patients.

Biomedical Imaging Research Opportunities Workshop III: A White Paper

The third Biomedical Imaging Research Opportunities Workshop (BIROW III) was held on March 11-12, 2005, in Bethesda, MD. The workshop addressed four areas of imaging that present opportunities for research and development: Multimodality Image-Guided Therapy, Imaging Informatics, Imaging Cell Trafficking, and Technology Improvement and Commercialization. The first three areas were individually addressed in their own plenary sessions, followed by audience discussions that explored research opportunities and challenges. This paper synthesizes these discussions into a strategy for future research directions in biomedical imaging.

Determining the minimum number of detectable cardiac-transplanted 111In-tropolone-labelled bone-marrow-derived mesenchymal stem cells by SPECT

In this work, we determined the minimum number of detectable 111In-tropolone-labelled bone-marrow-derived stem cells from the maximum activity per cell which did not affect viability, proliferation and differentiation, and the minimum detectable activity (MDA) of 111In by SPECT. Canine bone marrow mesenchymal cells were isolated, cultured and expanded. A number of samples, each containing 5x10(6) cells, were labelled with 111In-tropolone from 0.1 to 18 MBq, and cell viability was measured afterwards for each sample for 2 weeks. To determine the MDA, the anthropomorphic torso phantom (DataSpectrum Corporation, Hillsborough, NC) was used. A point source of 202 kBq 111In was placed on the surface of the heart compartment, and the phantom and all compartments were then filled with water. Three 111In SPECT scans (duration: 16, 32 and 64 min; parameters: 128x128 matrix with 128 projections over 360 degrees) were acquired every three days until the 111In radioactivity decayed to undetectable quantities. 111In SPECT images were reconstructed using OSEM with and without background, scatter or attenuation corrections. Contrast-to-noise ratio (CNR) in the reconstructed image was calculated, and MDA was set equal to the 111In activity corresponding to a CNR of 4. The cells had 100% viability when incubated with no more than 0.9 MBq of 111In (80% labelling efficiency), which corresponded to 0.14 Bq per cell. Background correction improved the detection limits for 111In-tropolone-labelled cells. The MDAs for 16, 32 and 64 min scans with background correction were observed to be 1.4 kBq, 700 Bq and 400 Bq, which implies that, in the case where the location of the transplantation is known and fixed, as few as 10,000, 5000 and 2900 cells respectively can be detected.

Molecular imaging of cell-based therapies

This article focuses on molecular imaging of novel cell-based therapies, particularly stem cell therapies and the adoptive transfer of immunocytes. The animal models,potential clinical applications, and likely future prospects of these therapies are discussed in the context of imaging.