Enhancing the bodies ability to create its own natural bypasses may soon become an alternative to baloon dilatation or bypass surgery. As reported in the February edition of Nature Biotechnology, scientists at the Max Planck Institute for Physiological and Clinical Research in Bad Nauheim/Germany have recently developed a non-invasive method to supply the diseased heart with vessel growth promoting factors making use of the property of microscopic beads to lodge in the peripheral vasculature. These beads are made to slowly release the growth factor without causing any damage.
Different growth factors have already been shown to promote the growth of new vessels. In particular Vascular Endothelial Growth Factor and Fibrobroblast Growth Factors have been subject to extensive research. However, whereas genes or proteins of these growth factors can simply be injected into peripheral tissues this is not possible in case of the heart. A systemic injection may also be deleterious since all of these growth factors have been shown to cause acute vascodilatation and may also promote tumor vessel growth. Attempts of vessel growth promoting therapies in the heart have therefore mainly been limited to cardiac surgery where the gene of a growth factor was given as adjunct to bypass surgery. The new method developed by Arras and collegues on the contrary requires only a routine catheterization procedure. Microscopic beads are injected into the vessel supplying the diseased territory and lodge in the peripheral capillary system whithout causing any damage. At this site they release the growth factor over a period of 7 days.
The major drawback of this method is that the growth factor will only be released within the diseased heart but not at the interface between healthy and diseased heart where large natural bypasses grow from smallest preexisting connections which are however large enough for the microscopic beads to pass through. The current method therefore is mainly suitable for situation in which many small vessels are diseased but not for bypassing a large stenosing coronary vessel.
The scientists at the Max Planck Instiute for Physiological and Clinical Research are currently directing their research efforts in deciphering the mechanism by which specialized blood cells locally adhere, release growth factors to preexisting connections between diseased and healthy areas of the heart, and thus stimulate the growth of true natural bypasses at exactly the location where it is needed.