Angiogenesis, or the development of new blood vessels, is a critical process in human biology. This development can occur as the extension of new blood vessels from existing vessels in the body
or as de novo formation (Patel & Mikos, 2004). Primarily, vasculogenesis, or the de novo formation, will occur during the developmental stages of an embryo.
Although, vasculogenesis has been shown to occur in adulthood as well. Angiogenesis from existing blood vessels occurs more frequently in adulthood as it as an important mechanism in multiple pathologies as well as wound healing (Bhise, Shmueli, Sunshine, Tzeng, & Green, 2011).
- Stages of Angiogenesis
Figure 1: Stages of Angiogenesis
- Types of Angiogenesis
Angiogenic Related Diseases
Growth Factors and Drugs Associated with Angiogenesis
- Early Stages
- Negative Side Effects
- Gene Delivery
- Cell Delivery
- Drug Delivery
As mentioned previously, angiogenesis is a critical mechanism during multiple disease states. Depending on the disease state, angiogenesis will be upregulated or downregulated.
Disease states that involve a downregulation or inhibition of angiogenesis leads to pathology including chronic wounds, myocardial ischemia, peripheral arterial disease, neuropathies, and more (Patel & Mikos, 2004).
Also, pro-angiogenesis is an essential step in organ transplant or integrating scaffolds into surrounding tissue. Vascular structure tends to be the limiting factor in engineered tissue replacements (Patel & Mikos, 2004).
On the other hand, diseases such as cancer, psoriasis, arthritis, asthma, Alzheimer’s disease, and macular degeneration involve an upregulation in angiogenesis that contributes to furthered pathogenesis.
In treating these various disease states, it is critical to utilize the correct growth factors or drugs that would elicit either a pro or anti-angiogenic response depending on the specific pathology.
Growth factors that are involved in the angiogenic process become critical at various stages during the process.
These early stage growth factors that are extremely critical in angiogenesis include VEGF, EGF, FGF, and TGF-beta.
VEGF is the most important growth factor in this process, but others have been studied as well including IGF-1 plasmid in promoting angiogenesis in vivo (Rabinovsky & Draghia-Akli, 2004) for example.
However, there are certain limitations involved with the delivery of growth factors as a therapeutic use.
Limitations of using and delivering growth factors as a therapeutic strategy include short half-lives, fast clearance rates, and off-target side-effects.
Additionally, if administering drugs systemically in small doses, there is an increased risk of drug resistance. Table 1 displays a variety of known growth factors and the associated effects.