7 replies to this topic

[John Schloendorn]

Please refer to the short descriptions and abstracts posted below. Voting ends Friday Oct 14 / 05.

Edited by John Schloendorn, 02 October 2005 - 03:48 PM.

[John Schloendorn]

Hombach A, Schlimper C, Sievers E, Frank S, Schild HH, Sauerbruch T, Schmidt-Wolf IG, Abken H. A recombinant anti-CEA immunoreceptor with combined CD3zeta - CD28 signalling targets T cells from colorectal cancer patients against their tumour cells. Gut 2005; [Epub ahead of print]

Summary & relevance:
A frequent way of cancer cells to escape the immune response is tolerizing it against tumor-specific antigens. These authors harvested mature T-cells from patients and transduced them with a fixed receptor against a tumor-specific antigen. The procedure was a success. Cancers were often recognized and regressed in human patients. It is heartening to see therapies that involve such a heavy degree of gene and cell engineering entering increasingly clinical applications, because that is what SENS will be relying on. The technique reported here will likely have further uses in the "too many", one of the 7 SENS threads referring to the specific destruction of unwanted, non-cancerous cells.

Abstract
BACKGROUND AND AIMS: The prognosis of metastatic colorectal cancer is still poor rising the need for alternative therapeutic approaches, particularily by manipulating the anti-tumor immune response. Advanced tumor stages, however, are frequently accompanied by functional T cell defects which may be critical for a T cell based anti-cancer immunotherapy. The aim of this study was to address whether T cells from colorectal cancer patients with advanced tumor stages can be antigen- specifically activated against their autologous tumor cells. METHODS: T cells were isolated from colorectal cancer patients and retrovirally transduced to express a recombinant immunoreceptor that has an extracellular binding domain for carcinoembryonic antigen (CEA) and an intracellular CD3zeta signalling domain with and without CD28 costimulation for T cell activation. RESULTS: Peripheral blood T cells from colorectal cancer patients were successfully engineered to express the anti-CEA immunoreceptor on the cell surface. Upon coincubation with autologous CEA+ tumor cells, T cells with anti-CEA immunoreceptor are specifically activated to secrete IFN-gamma and to lyse the autologous tumor cells whereas T cells without immunoreceptor are not. T cells equipped with combined CD3zeta - CD28 signalling receptor are more efficiently activated to secrete IFN- gamma compared to T cells with CD3zeta signalling receptor. Induction of IL2 secretion upon targeting towards autologous tumor cells requires triggering of T cells by the CD3zeta-CD28 costimulatory receptor. CONCLUSIONS: T cells from advanced colorectal cancer patients can be tumor-specifically activated with high efficiency by engraftment with a combined CD3zeta- CD28 immunoreceptor to break tolerance against autologous tumor cells.

[John Schloendorn]

Lindenbaum M, Perkins E, Csonka E, Fleming E, Garcia L, Greene A, Gung L, Hadlaczky G, Lee E, Leung J, MacDonald N, Maxwell A, Mills K, Monteith D, Perez CF, Shellard J, Stewart S, Stodola T, Vandenborre D, Vanderbyl S, Ledebur HC Jr. A mammalian artificial chromosome engineering system (ACE System) applicable to biopharmaceutical protein production, transgenesis and gene-based cell therapy. Nucleic Acids Res. 2004; 32(21):e172.

Summary & relevance
Mammalian artificial chromosomes (MACs) remain the only method to reliably and permanently introduce large payloads of transgene into human cells. The authors here describe a system based on site-specific recomination that allows the construction of customized MACs that can be loaded with a large number of different transgenes while intuitively controlling each gene's position and copy number. MACs will likely be the major vehicle of many SENS interventions that require the introduction of large amounts of transgene, such as allotopic expression, medical bioremediation or WILT.

Abstract
Mammalian artificial chromosomes (MACs) provide a means to introduce large payloads of genetic information into the cell in an autonomously replicating, non-integrating format. Unique among MACs, the mammalian satellite DNA-based Artificial Chromosome Expression (ACE) can be reproducibly generated de novo in cell lines of different species and readily purified from the host cells' chromosomes. Purified mammalian ACEs can then be re-introduced into a variety of recipient cell lines where they have been stably maintained for extended periods in the absence of selective pressure. In order to extend the utility of ACEs, we have established the ACE System, a versatile and flexible platform for the reliable engineering of ACEs. The ACE System includes a Platform ACE, containing >50 recombination acceptor sites, that can carry single or multiple copies of genes of interest using specially designed targeting vectors (ATV) and a site-specific integrase (ACE Integrase). Using this approach, specific loading of one or two gene targets has been achieved in LMTK(-) and CHO cells. The use of the ACE System for biological engineering of eukaryotic cells, including mammalian cells, with applications in biopharmaceutical production, transgenesis and gene-based cell therapy is discussed.

[John Schloendorn]

Hwang WS, Roh SI, Lee BC, Kang SK, Kwon DK, Kim S, Kim SJ, Park SW, Kwon HS, Lee CK, Lee JB, Kim JM, Ahn C, Paek SH, Chang SS, Koo JJ, Yoon HS, Hwang JH, Hwang YY, Park YS, Oh SK, Kim HS, Park JH, Moon SY, Schatten G. Patient-specific embryonic stem cells derived from human SCNT blastocysts. Science. 2005; 308(5729):1777-83.

Summary & relevance:
Who has not heard of the legendary South Korean experiment that yielded immune-compatible cloned human embryonic stem cell lines for 11 patients at greatly increased efficiency in comparison to earlier methods? This small and hardly recognized country seems to be the only one that values the health of a human patient higher than the right of an aborted embryo to rot in a rubbish can. Here they come to the rescue of the citizens of earth whose other governments logjammed themselves in cruel conservativism cynically labeled "ethics" by some.

Abstract
Patient-specific, immune-matched human embryonic stem cells (hESCs) are anticipated to be of great biomedical importance for studies of disease and development and to advance clinical deliberations regarding stem cell transplantation. Eleven hESC lines were established by somatic cell nuclear transfer (SCNT) of skin cells from patients with disease or injury into donated oocytes. These lines, nuclear transfer (NT)-hESCs, grown on human feeders from the same NT donor or from genetically unrelated individuals, were established at high rates, regardless of NT donor sex or age. NT-hESCs were pluripotent, chromosomally normal, and matched the NT patient's DNA. The major histocompatibility complex identity of each NT-hESC when compared to the patient's own showed immunological compatibility, which is important for eventual transplantation. With the generation of these NT-hESCs, evaluations of genetic and epigenetic stability can be made. Additional work remains to be done regarding the development of reliable directed differentiation and the elimination of remaining animal components. Before clinical use of these cells can occur, preclinical evidence is required to prove that transplantation of differentiated NT-hESCs can be safe, effective, and tolerated.

[John Schloendorn]

Little WC, Zile MR, Kitzman DW, Hundley WG, O'Brien TX, Degroof RC. The effect of alagebrium chloride (ALT-711), a novel glucose cross-link breaker, in the treatment of elderly patients with diastolic heart failure. J Card Fail. 2005; 11(3):191-5.

Summary & relevance
Breakers of extracellular matrix protein crosslinks are the most advanced of the 7 SENS threads. Here the famous ALT-711 is reported to improve the condition of sufferers from a certain form of heart failure, by restoring chemical integrity and mechanical compliance to their aged hearts and arterial walls.

Abstract
BACKGROUND: Despite its high prevalence, optimal therapy for diastolic heart failure (DHF) has not been determined. Alagebrium chloride (ALT-711) is a novel compound that breaks glucose crosslinks and may improve ventricular and arterial compliance. METHODS AND RESULTS: A total of 23 patients, mean age 71 years, with stable DHF, ejection fraction (EF) >50%, were enrolled in a 16-week, open-label trial of alagebrium 420 mg per day. Assessments included: peak exercise oxygen consumption, aortic distensibility, and left ventricular EF and mass by magnetic resonance imaging, Doppler diastolic filling, and quality of life by the Minnesota Living with Heart Failure questionnaire. One patient discontinued treatment because of a myocardial infarction after 12 days of treatment, and a second died suddenly after 10 weeks of treatment. Thus 21 patients completed the study. Left ventricular mass was 124 +/- 35 g at baseline and decreased to 119 +/- 34 g at follow up ( P = .036). This was accompanied by a decrease in the ratio of Doppler early diastolic flow velocity to Doppler early diastolic mitral annulus velocity (E') from 10.6 +/- 2.7 to 9.4 +/- 1.9 ( P = .076) and an increase in E' from 7.3 +/- 1.2 to 8.4 +/- 1.7 cm/s ( P = .045). The Minnesota Living with Heart Failure total score improved from 41 +/- 21 to 32 +/- 21 ( P = .01). There were no changes in EF (64 +/- 4% at baseline), blood pressure, peak exercise oxygen consumption, and aortic distensibility. CONCLUSION: Sixteen weeks of treatment with the glucose crosslink breaker, alagebrium, resulted in a decrease in left ventricular mass and improvements in left ventricular diastolic filling and quality of life in patient with DHF.

[John Schloendorn]

Matheu A, Pantoja C, Efeyan A, Criado LM, Martin-Caballero J, Flores JM, Klatt P, Serrano M. Increased gene dosage of Ink4a/Arf results in cancer resistance and normal aging. Genes Dev. 2004 Nov 15;18(22):2736-46.

Summary & relevance
Tumor suppressor mechanisms (e.g. cell senescence, apoptosis) have often been implicated in aging. By arresting dividing cells, it was found in various cases that they can impair healthy function and regeneration. Here, on the contrary, a transgenic mouse carrying an extra copy of the potent Ink4a/Arf tumor suppressor gene is reported to have greatly reduced tumor incidence, but age at a normal rate. This type of strategy will become important for life-extension either when we develop safe and effective gene therapy (to introduce such tumor suppressors in our existing cells), or when we extend life that much that we need to fear tumors arising from any replacement cells we might have received. It is, however, very hard to test such long term preventive interventions in humans.

Abstract
Mammalian genes frequently present allelic variants that differ in their expression levels and that, in the case of tumor suppressor genes, can be of relevance for cancer susceptibility and aging. We report here the characterization of a novel mouse model with increased activity for the Ink4a and Arf tumor suppressors. We have generated a "super Ink4a/Arf" mouse strain carrying a transgenic copy of the entire Ink4a/Arf locus. Cells derived from super Ink4a/Arf mice have increased resistance to in vitro immortalization and oncogenic transformation. Importantly, super Ink4a/Arf mice manifest higher resistance to cancer compared to normal, nontransgenic, mice. Finally, super Ink4a/Arf mice have normal aging and lifespan. Together, these results indicate that modest increases in the activity of the Ink4a/Arf tumor suppressor result in a beneficial cancer-resistant phenotype without affecting normal viability or aging.

[Bruce Klein]

Again, splendid work here, John... excellent "summary & relevance" overviews.

[John Schloendorn]

There we go, a draw! Starting a runoff poll...