**1. Introduction**

Regenerative concepts are one of the basic ideas of modern biomedical research. Regeneration means origination in stark contrast to substitution. This process aims not to replace or to reconstruct but to restore the physical integrity of cells, tissues and organs by means of the organisms' own repair mechanisms.

Especially the regeneration of neuronal tissues has been in the focus of interest, but these restorative concepts will also become applicable in the treatment of metabolic or degenerative diseases. Gentherapy and tissue engineering procedures are two established areas of research in which regeneration plays a major role and has already proven its significance.

The fundament of regeneration is the tissue's potential to grow, to differentiate and therefore to continually bridge permanently emerging damages. It is a stepless coexistence of build-up and degradation processes in which a plethora of enzymes, signal proteins, ligands and their corresponding receptors on different regulatory levels are involved. These processes concern everypartofthebody;theleastcommondenominatorofallthesephysiologicaleventsthatinclude atransitionfromsinglecellstoacomplextissuestructureistheirdemandforenergyandsubstrates. It becomes obvious that there can never arise a regenerative course without a functioning vasculature to provide the essential cells and proteins, to ensure the oxygen and nutrient supply and to evacuate accumulating metabolic products. Any regeneration is only able to develop with a simultaneously developing vessel system. The realisation seems to be trivial, but the vital importance of a functional vasculature is not generally considered in regenerative concepts.

On the following pages the role of vasculogenesis and angiogenesis in regeneration is to be described; after a depiction of the angiogenic cascade, the regulation by hypoxia is tracked. From the description of the physiological molecular course of the angiogenic cascade and the interrela‐ tion of its key protagonists we trace the impact of macro- and microscopic vascularisation in various regenerative processes and clarify its central position in tissue engineering models.

© 2013 Jung and Kleinheinz; licensee InTech. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2013 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Finally the role of pluripotent cells in modern tissue engineering concepts is summarized.

Fundamental research with special respect to cell culture, immunohistochemistry, in vitro and in vivo trials, circulation modelling and gene expression profiling provides the scientific basis for this survey.
