Harvard Stem Cell Institute Research Newsletter
| |
| | | |  | Research Commentary Stem cell imaging; a vital player in the drive toward therapeutics by Lisa Girard, PhD
HSCI Science Editor Progress in stem cell tracking and imaging is critical to the advancement of stem cell-based therapeutics. Reliable in vivo imaging techniques contribute to the potential for stem cell-based gene therapy treatments by identifying and isolating stem cell pools and following stem cell engraftment. Demonstrating the safety of stem cell-based therapeutics is an important hurdle in the path to FDA approval. Tracking transplanted cells and determining where they go and how long they remain in their intended location are critical parameters for understanding the safety of a procedure. Innovative stem cell–based gene therapy and imaging techniques have recently been successfully coupled to deliver anti-tumor therapeutics. Glioblastomas are the most common form of malignant brain tumor and they carry an unfortunate prognosis, with most patients surviving for about two years after diagnosis. New opportunities for stem-cell based treatments for glioblastomas emerged when it was found that transplanted neural precursor cells (NPCs) could migrate and integrate themselves within the central nervous system. Researchers working with Xandra Breakefield of Harvard's Massachusetts General Hospital, including HSCI's Ralph Weissleder (1), engineered NPCs with a type of tumor necrosis factor-related apoptosis-inducing ligand known as S-TRAIL, which can specifically induce cell death in tumor cells when the engineered NPCs are implanted into the head of mice. Researchers were able to visualize this process by including luminescent and bioluminescence transgenes in the NPCs for use in dual bioluminescence imaging. Using this imaging technique, researchers could observe the NPCs migrating to the site and exerting their cell death-inducing properties. 2006 HSCI Seed Grant recipient Rona Carroll and her group at Harvard's Brigham and Women's Hospital also describe tracking methods integral to the success of their research. Carroll and colleagues investigated whether the NPCs could serve as effective anti-tumor drug delivery modules for medulloblastoma, an often-incurable pediatric brain tumor (2). For studies in mice, NPCs were labeled with chloromethylbenzamido-DiI (CM-DiI). CM-DiI is a non-diffusible probe that has been found to be useful for tracking cells for at least two and a half months. The group tested the therapeutic potential of their system using the CD enzyme/5-FC system. CD is a bacterial enzyme that converts the nontoxic 5-FC to the cytotoxic drug 5-FU (5-fluorocytosine to 5-fluorouracil), which disrupts DNA synthesis in proliferating cells by acting as a nucleotide analog. Tumor cells transfected with the E. coli CD gene become susceptible to 5-FU toxicity. This system also has a "bystander effect" that causes the death of tumor cells adjacent to those modified with CD. The CD gene is an example of a "suicide gene" that can not only destroy tumor cells, but can also destroy itself if it starts dividing - a useful feature since tumor formation from transplanted stem cells can be a significant issue. The imaging approaches used in these instances enabled the researchers to gauge whether their anti-tumor methods were working as intended, facilitating progress in the cell-based drug delivery arena. These types of approaches that specifically target tumor cells contribute to the growing trend in therapeutics from systemic to localized delivery, reducing side effects caused by widespread cellular toxicity. Neri et al. (3) from the Stem Cell Research Institute in Italy describe another approach to imaging NPCs. They tracked human NPCs using magnetic resonance (MR) tracking of superparamagnetic iron oxide (SPIRO)-labeled cells. In this method, cells are magnetically labeled using the SPIRO particles, making them traceable by MRI. Studies in mice found that cells could be tracked for up to a month using these methods. This technique has also been used in human mesenchymal and hematopoietic stem cells and is an example of the type of sensitive, non-invasive approach that could be useful for monitoring cell therapy approaches allowing researchers to track transplanted cells in longitudinal studies. Another approach that is being explored with growing interest for non-invasive in vivo imaging is the use of quantum dots. Quantum dots are fluorescent probes that are excited by one wavelength and emit light at different wavelengths, making them ideal for complex imaging. They are also very bright and resistant to photobleaching, important features for probes used in the longitudinal tracking of small numbers of cells. Fluorescent probes that have been used previously are limited in the number of colors they can emit and may emit an overly broad spectrum, making them difficult to use for complex imaging. The brightness of quantum dots is a positive feature for stem cell imaging because its signal is bright enough that it may be less likely to diffuse within tissue. A recent study by Lin et al. (4) at Stanford used quantum dots to label mouse embryonic stem cells. The authors show that the probes do not affect the stem cell's viability, proliferation, or differentiation, making them potentially useful probes. Issues including improving cell retention of the probes must be resolved, however, before quantum dots are optimal probes for longitudinal tracking of stem cell transplants. As we move toward more viable stem cell-based therapeutics, we will see a tight coupling between advances in stem cell biology and advances in imaging that biology. Developments in the areas of long lasting, MR-traceable, and non-diffusible imaging probes are enabling researchers to extend longitudinal studies. This will facilitate the development of new stem cell based therapeutics as cell tracking becomes easier, as well as speed their path from bench to bedside as safety and efficacy can be demonstrated more quickly and directly. References - Cowan, C.A., Atienza, J., Melton, D.A., Eggan, K. (2005). Science 309, 1369-73.
- Okita, K., Ichisaka, T., Yamanaka, S. (2007) Nature 448, 313-7.
- Hanna J, Wernig M, Markoulaki S, Sun CW, Meissner A, Cassady JP, Beard C, Brambrink T, Wu LC, Townes TM, Jaenisch R Science. 2007 Dec 6 [Epub ahead of print]
- Hyun, I., Hochedlinger, K., Jaenisch, R., Yamanaka, S. (2007) Cell Stem Cell 1, 367-368.
- Maherali, N., Sridharan, R., Xie, W., Utikal, J., Eminli, S., Arnold, K., Stadtfeld, M., Yachechko, R., Tchieu, J., Jaenisch, R., Plath, K., Hochedlinger, K. (2007) Cell Stem Cell 1, 55-70.
- Okita, K., Ichisaka, T., Yamanaka, S. (2007) Nature 448, 313-7.
- Takahashi, K., and Yamanaka, S. (2006). Cell 126, 663-676.
- Wernig M, Meissner A, Foreman R, Brambrink T, Ku M, Hochedlinger K, Bernstein BE, Jaenisch R. (2007) Nature 448, 318-24.
| | | Spotlight Article Reprogramming of human somatic cells to pluripotency with defined factors Researchers at the Harvard Stem Cell Institute and Childrens Hospital Boston have converted skin cells from an adult into cells that look and act like embryonic stem cells. The resulting cell lines, called induced pluripotent stem cells (iPS), can potentially form any cell type in the body. iPS cells allow a new way for scientists to model human diseases and may one day provide raw material for cell therapies to reverse leukemia, diabetes, Parkinson's disease, and paralysis, among other devastating conditions. The study, led by first-author In Hyun Park, PhD, is similar to reports from laboratories in Japan and the University of Wisconsin that gained worldwide attention in November. However, this study is the first to use tissue from a volunteer research subject rather than cells purchased commercially. "Ours is the only group to go from skin biopsy to cell line," says George Q. Daley, MD, PhD, HSCI Principal Faculty and Executive Committee Member, and the study's senior author. "We developed a strategy that integrates tissue procurement, culturing, and reprogramming the cells. We're now ready to apply this method to cells from patients with a variety of diseases." Park IH, Zhao R, West JA, Yabuuchi A, Huo H, Ince TA, Lerou PH, Lensch MW, Daley GQ. Reprogramming of human somatic cells to pluripotency with defined factors. Nature. 2007 Dec 23. Read Abstract. | Review and Commentary Articles - Ptaszek LM, Cowan CA. New Tools for Genome Modification in Human Embryonic Stem Cells. Cell Stem Cell. 2007 Dec 13:1(6):600-602. Read Abstract.
- Scadden DT. The weight of cell identity. J Clin Invest. 2007 Dec;117(12):3653-5. Read Abstract.
| Cancer - Gee MS, Upadhyay R, Bergquist H, Weissleder R, Josephson L, Mahmood U. Multiparameter noninvasive assessment of treatment susceptibility, drug target inhibition and tumor response guides cancer treatment. Int J Cancer. 2007 Dec 1;121(11):2492-500. Read Abstract.
- Li Z, Tognon CE, Godinho FJ, Yasaitis L, Hock H, Herschkowitz JI, Lannon CL, Cho E, Kim SJ, Bronson RT, Perou CM, Sorensen PH, Orkin SH. ETV6-NTRK3 Fusion Oncogene Initiates Breast Cancer from Committed Mammary Progenitors via Activation of AP1 Complex. Cancer Cell. 2007 Dec;12(6):542-58. Read Abstract.
- Fröhling S, Scholl C, Levine RL, Loriaux M, Boggon TJ, Bernard OA, Berger R, Döhner H, Döhner K, Ebert BL, Teckie S, Golub TR, Jiang J, Schittenhelm MM, Lee BH, Griffin JD, Stone RM, Heinrich MC, Deininger MW, Druker BJ, Gilliland DG. Identification of Driver and Passenger Mutations of FLT3 by High-Throughput DNA Sequence Analysis and Functional Assessment of Candidate Alleles. Cancer Cell. 2007 Dec;12(6):501-13. Read Abstract.
- Swanson KD, Winter JM, Reis M, Bentires-Alj M, Greulich H, Grewal R, Hruban RH, Yeo CJ, Yassin Y, Iartchouk O, Montgomery K, Whitman SP, Caligiuri MA, Loh ML, Gilliland DG, Look AT, Kucherlapati R, Kern SE, Meyerson M, Neel BG. SOS1 mutations are rare in human malignancies: Implications for Noonan syndrome patients. Genes Chromosomes Cancer. 2007 Dec 6;47(3):253-259. Read Abstract.
- Gounaris E, Erdman SE, Restaino C, Gurish MF, Friend DS, Gounari F, Lee DM, Zhang G, Glickman JN, Shin K, Rao VP, Poutahidis T, Weissleder R, McNagny KM, Khazaie K. Mast cells are an essential hematopoietic component for polyp development. Proc Natl Acad Sci USA. 2007 Dec 11;104(50):19977-82. Read Abstract.
- Del Gaizo Moore V, Schlis KD, Sallan SE, Armstrong SA, Letai A. BCL-2 dependence and ABT-737 sensitivity in acute lymphoblastic leukemia. Blood. 2007 Dec 4. Read Abstract.
| Cardiovascular System - Yamamoto R, Akazawa H, Ito K, Toko H, Sano M, Yasuda N, Qin Y, Kudo Y, Sugaya T, Chien KR, Komuro I. Angiotensin II type 1a receptor signals are involved in the progression of heart failure in MLP-deficient mice. Circ J. 2007 Dec;71(12):1958-64. Read Abstract.
| Developmental Biology - Rompani SB, Cepko CL. Retinal progenitor cells can produce restricted subsets of horizontal cells. Proc Natl Acad Sci USA. 2007 Dec 27. Read Abstract.
- Park IH, Zhao R, West JA, Yabuuchi A, Huo H, Ince TA, Lerou PH, Lensch MW, Daley GQ. Reprogramming of human somatic cells to pluripotency with defined factors. Nature. 2007 Dec 23. Read Abstract.
| Diabetes - Marselli L, Thorne J, Ahn YB, Omer A, Sgroi DC, Libermann T, Otu HH, Sharma A, Bonner-Weir S, Weir GC. Gene expression of purified beta cell tissue obtained from human pancreas with laser capture microdissection. J Clin Endocrinol Metab. 2007 Dec 11. Read Abstract.
- Papas KK, Pisania A, Wu H, Weir GC, Colton CK. A stirred microchamber for oxygen consumption rate measurements with pancreatic islets. Biotechnol Bioeng. 2007 Dec 1;98(5):1071-82. Read Abstract.
| Imaging - Korngold EC, Jaffer FA, Weissleder R, Sosnovik DE. Noninvasive imaging of apoptosis in cardiovascular disease. Heart Fail Rev. 2007 Dec 12. Read Abstract.
- Harisinghani M, Ross RW, Guimaraes AR, Weissleder R. Utility of a new bolus-injectable nanoparticle for clinical cancer staging. Neoplasia. 2007 Dec;9(12):1160-5. Read Abstract.
- Nahrendorf M, Zhang H, Hembrador S, Panizzi P, Sosnovik DE, Aikawa E, Libby P, Swirski FK, Weissleder R. Nanoparticle PET-CT Imaging of Macrophages in Inflammatory Atherosclerosis. Circulation. 2007 Dec 24. Read Abstract.
- Bouffard J, Kim Y, Swager TM, Weissleder R, Hilderbrand SA. A highly selective fluorescent probe for thiol bioimaging. Org Lett. 2008 Jan 3;10(1):37-40. Epub 2007 Dec 7. Read Abstract.
| Immunology - Noor S, Goldfine H, Tucker DE, Suram S, Lenz LL, Akira S, Uematsu S, Girotti M, Bonventre JV, Breuel K, Williams DL, Leslie CC. Activation of cytosolic phospholipase A2alpha in resident peritoneal macrophages by Listeria monocytogenes involves listeriolysin O and TLR2. J Biol Chem. 2007 Dec 14. Read Abstract.
| Nervous System - Gao X, Arlotta P, Macklis JD, Chen J. Conditional knock-out of beta-catenin in postnatal-born dentate gyrus granule neurons results in dendritic malformation. J Neurosci. 2007 Dec 26;27(52):14317-25. Read Abstract.
- Chang BS, Katzir T, Liu T, Corriveau K, Barzillai M, Apse KA, Bodell A, Hackney D, Alsop D, Wong S, Walsh CA. A structural basis for reading fluency: white matter defects in a genetic brain malformation. Neurology. 2007 Dec 4;69(23):2146-54. Read Abstract.
- Rajab A, Manzini MC, Mochida GH, Walsh CA, Ross ME. A novel form of lethal microcephaly with simplified gyral pattern and brain stem hypoplasia. Am J Med Genet A. 2007 Dec 1;143(23):2761-7. Read Abstract.
| Renal System - van Timmeren MM, Vaidya VS, van Ree RM, Oterdoom LH, de Vries AP, Gans RO, van Goor H, Stegeman CA, Bonventre JV, Bakker SJ. High Urinary Excretion of Kidney Injury Molecule-1 Is an Independent Predictor of Graft Loss in Renal Transplant Recipients. Transplantation. 2007 Dec 27;84(12):1625-1630. Read Abstract.
- Zhang PL, Rothblum LI, Han WK, Blasick TM, Potdar S, Bonventre JV. Kidney injury molecule-1 expression in transplant biopsies is a sensitive measure of cell injury. Kidney Int. 2007 Dec 26. Read Abstract.
- Han WK, Waikar SS, Johnson A, Betensky RA, Dent CL, Devarajan P, Bonventre JV. Urinary biomarkers in the early diagnosis of acute kidney injury. Kidney Int. 2007 Dec 5. Read Abstract.
| Technology - Wang J, Theunissen TW, Orkin SH. Site-directed, virus-free, and inducible RNAi in embryonic stem cells. Proc Natl Acad Sci USA. 2007 Dec 26;104(52):20850-5. Read Abstract.
| The Harvard Stem Cell Institute is a scientific collaborative established to fulfill the promise of stem cell biology as the basis for cures and treatments for a wide range of chronic medical conditions. Visit our website at www.hsci.harvard.edu. If there is anything that you would like to see added to this email alert, please email maureen_lyons@harvard.edu. | |
| |
