A step forward in ways to replace damaged or diseased human organs is by 3-D printing new organs. Successful trials are promising. Yet, a huge challenge is to create a vascular system to provide blood supply to those organ tissues. In the case of heart replacement, spinach might be the answer. The structure of spinach leaves may offer the answer as a viable blood vessel “plumbing” system. Check out the research at http://news.nationalgeographic.com/2017/03/human-heart-spinach-leaf-medicine-science.