New sources of red blood cells (RBCs) could radically improve the transfusion capacity of many hospitals, and Luc Douay and his team at Hopital Armand Trousseau and other hospitals in the Paris area have investigated the potential for producing substantial quantities of RBCs from human cord blood. The French researchers have described in Nature Biotechnology a procedure for amplifying the number of hemapoietic stem cells from human cord blood into a pure erythroid precursor population. On a basis of a 200,000-fold cell amplification achieved after 17 days of culture, they predict that a starting population of 106 CD34+ cells could produce 40g to 50g of hemoglobin after completing terminal maturation in vivo.
Douay notes that cryopreservation of cord blood would ensure long-term viral security and the production of up to three units of packed red cells from a single cord blood donor would also reduce viral contamination risks. Furthermore, the residual leukocyte count in the expanded product is three to 50 times less than in a classical packed cell product.
In essence, the French group has developed a method for large-scale expansion of erythroid cells from cord blood human stem cells by the sequential application of a series of growth factors. They also have shown that the erythroid precursor cells produced are capable of completing maturing in vivo in animal trials all the way through to mature red blood cells containing functional adult hemoglobin.
The next stage will be the adapting of these laboratory methodologies to larger scale production systems in blood banks. It may be that as a result the transfusion of ex vivo expanded erythroid precursor cells may become a routine complementary approach in many blood transfusion procedures.
Stem cell therapy in end-stage disease
Cardiologists at the John Hunter Medical Research Institute (Newcastle, Australia) have started a clinical trial using endothelial stem cells from the bone marrow of patients with end stage coronary disease and injecting them directly into the heart muscle of the left ventricle to revascularize the patients' hearts. These cells have the capability to form new blood vessels and also to deliver hormones like vascular endothelial growth factor (VEGF) to stimulate blood vessel growth.
Delivery of the progenitor stem cells into the muscle uses a catheter guidance system, NOGA, being developed by Biosense Webster (Sydney, Australia), a subsidiary of Johnson & Johnson (New Brunswick, New Jersey). "It's just like GPS; it uses three reference magnets like satellites positioned under the operating table," said Suku Thambar, the cardiologist heading the team in Newcastle.
The procedure follows from successful animal trials carried out last year by Shmuel Fuchs at the Washington Hospital Center's (Washington) Cardiovascular Research Institute. Fuchs assisted the Newcastle team with the injection of the stem cells into the human patients. Earlier trials on end-stage coronary disease patients at the Queen Mary Hospital in Hong Kong, conducted by Professor Hung Fat Tse, established safety and feasibility, and the Newcastle trials involving 36 patients are the first randomized blinded trials on a multicenter basis.
Non-invasive angiography by MRI
Researchers at Leiden University Medical Center (Leiden, the Netherlands) have shown that high-resolution magnetic resonance angiography (MRA) can identify blockage in vein grafts after bypass surgery and also the extent of the narrowing. Coronary angiography is a routine methodology for diagnosing blocked arteries, but its use can be dangerous after bypass surgery. The researchers used high-resolution MRA to assess the condition of 56 leg vein grafts in 38 patients with a mean age of 67 and who had complained of chest pains after bypass surgery.
The diagnostic accuracy achieved in vessels with a complete blockage was 83% by MRA compared to 100% by traditional invasive angiography. In vessels narrowed by 70% or more, MRA accuracy was 73% compared to 87% by angiography. In vessels narrowed by 50%, the accuracy of MRA was 65% against 88% for angiography. The researchers, led by Ernst van der Wall, professor of cardiology at Leiden, conclude that high-resolution MRA cannot yet replace coronary angiography, but it could be regarded as a useful adjunct. The cost of an MRA is about half of that of an angiography and it is completely noninvasive, said van der Wall.
MedNova starts angioplasty filter trial
MedNova (Galway, Ireland) has develop the CardioShield filter device for use in capturing particles in the blood released during an angioplasty procedure. A catheter is used to pass the basket filter through an artery and position in the vein graft just beyond the blockage. After opening the artery with balloon angioplasty and placing of a stent, the basket plus contents can be collapsed into a retrieval catheter. MedNova is sponsoring an 800-patient study on the CardioShield device against a currently available balloon device in angioplasty procedures. The trial is being conducted at the University of Pittsburgh Medical Center (Pittsburgh, Pennsylvania).
Myocardial revascularization in France
Professor Jacques Puel of the University Hospital Purpan (Toulouse, France) estimates that about 130,000 patients last year benefitted from a revascularization procedure in France, with three-quarters (almost 100,000) by angioplasty and 32,000 to 33,000 bypass surgeries. He estimates the risk of restenosis following angioplasty as being in the region of 10%, but is confident that new generations of active stents will reduce this proportion substantially.
Noninvasive stress testing
Inert gas rebreathing (IGR) methodologies have over the past fifty years been compared in numerous studies to invasive methods such as thermodilution, dye dilution and direct Fick, with good agreement shown between IGR and invasive alternatives. Most studies have used a mass spectrometer to measure inert gases, severely limiting.the practical usefulness of IGR. Innovision (Odense, Denmark) has developed the Innocor system, which uses photoacoustic infrared light detection to measure inert gases and thus cardiac output. The device, originally developed for use in the International Space Station, requires almost no operator skills and can readily be used on a point-of-care basis in the noninvasive measurement of cardiac output.
New SED has teletransmission facility
Schiller (Baar, Switzerland) has launched its latest semi-automatic defibrillator that includes an additional data-transmission feature. The First Responder External Defibrillator (FRED) unit incorporates Multipulse Biowave technology that is claimed to be highly effective pulsed energy, which has a more gentle impact on the heart tissue. In addition, by pressing a single key, a 12-lead standard ECG can be transmitted via a GSM or satellite cellular telephone for analysis and storage on any computer system. Professional analysis and storage is provided by Schiller's SEMA-200 Data Management Software.
Roche licenses rights to RBC booster
Roche (Basel, Switzerland) has licensed all rights to Gryphon Sciences' (South San Francisco, California) Synthetic Erythropoiesis Protein (SEP), a synthetic protein made using Gryphon technology. SEP will be developed by Roche to alleviate conditions causing anemia, such as the treatment of cancer with chemotherapy and the hemodialysis of patients with renal failure.