Severed Ties (1992)

Harrison is a young scientist who grew up under the thumb of his rich, posh, and domineering mother Helena. Even in his adulthood she still has a stranglehold over him, since she's financing his research based on the discoveries of his late scientist father. His obsession is to successfully use lizard DNA to stimulate regeneration of dead or dying tissue, which could lead to cure for cancer or even regeneration of lost limbs in humans. He soon has a breakthrough, but all his dreams are crushed when he learns that his manipulative mother and her unscrupulous boyfriend Dr. Hans Vaughn are planing to take all of his research from him and sell it as their own. Enraged, Harrison has an argument with his mother and Vaughn that ends in tragedy when an automated door accidentally severs his right arm. Harrison injects himself with his regeneration serum to try to grow a new hand. Unfortunately, it turns out that his new scaly limb has a killer mind of its own. Harrison runs away and finds shelter in the sewers with a bunch of homeless crippled war veterans led by Stripes. Harrison decides to use his serum on them in an attempt to get them to help him get his research back.