UCLA
stem cell 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.
Adipose,
or fat, tissue is thought to be an ideal source of cells called
mesenchymal stem cells—capable of developing into bone, cartilage,
muscle and other tissues—because they are plentiful and easily
attained through procedures such as liposuction, said Dr. Chia Soo, vice
chair for research at UCLA Plastic and Reconstructive Surgery. The
co-senior authors on the project, Soo and Bruno Péault, are members of
the Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell
Research at UCLA.
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. A fresh, non-cultured cell
composition called stromal vascular fraction (SVF) also is used to grow
bone. However, SVF cells taken from adipose tissue are a highly
heterogeneous population that includes cells that aren’t capable of
becoming bone.
Péault
and Soo’s team 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 than SVF cells in creating bone. They also
showed that a growth factor called NELL-1, discovered by Dr. Kang Ting
of the UCLA School of Dentistry, 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,” Soo said. “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 study appears June 11, 2012 in the early online edition of the peer-reviewed journal Stem Cells Translational Medicine, a new journal that seeks to bridge stem cell research and clinical trials.
In
the animal model, Soo and Péault’s team put the hPSCs with NELL-1 in a
muscle pouch, a place where bone is not normally grown. They then used
X-rays to determine that the cells did indeed become bone.
“The
purified human hPSCs formed significantly more bone in comparison to
the SVF by all parameters,” Soo said. “And these cells are plentiful
enough that patients with not much excess body fat can donate their own
fat tissue.”
Soo
said 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, Soo said.
“Excitingly,
recent studies have already demonstrated the utility of perivascular
stem cells for regeneration of disparate tissue types, including
skeletal muscle, lung and even myocardium,” said Péault, a professor of
orthopedic surgery “Further studies will extend our findings and apply
the robust osteogenic potential of hPSCs to the healing of bone
defects.”
Broad Stem Cell Research Center
Source: University of California – Los Angeles Health Sciences
