An example of the sort of work presently taking place in the stem cell field: "scientists purified a subset of stem cells found in fat tissue and made from them bone that was formed faster and was of higher quality than bone grown using traditional methods, a finding that may one day eliminate the need for painful bone grafts that use material taken from the patient during invasive procedures. ... Traditionally, cells taken from fat had to be cultured for weeks to isolate the stem cells which could become bone, and their expansion increases risk of infection and genetic instability. ... [Researchers] used a cell sorting machine to isolate and purify human perivascular stem cells (hPSC) from adipose tissue and showed that those cells worked far better. They also showed that a growth factor called NELL-1 [enhanced] the bone formation in their animal model. ... People have shown that culture-derived cells could grow bone, but these are a fresh cell population and we didn't have to go through the culture process, which can take weeks. The best bone graft is still your own bone, but that is in limited supply and sometimes not of good quality. What we show here is a faster and better way to create bone that could have clinical applications. ... The purified human hPSCs formed significantly more bone [and] these cells are plentiful enough that patients with not much excess body fat can donate their own fat tissue. ... if everything goes well, patients may one day have rapid access to high quality bone graft material by which doctors get their fat tissue, purify that into hPSCs and replace their own stem cells with NELL-1 back into the area where bone is required. The hPSC with NELL-1 could grow into bone inside the patient, eliminating the need for painful bone graft harvestings. The goal is for the process to isolate the hPSCs and add the NELL-1 with a matrix or scaffold to aid cell adhesion to take less than an hour."