Monday, November 8, 2010

Stem Cells

The October issue of the Plastic and Reconstructive Surgery Journal has a nice review article of stem cells (bold emphasis is mine).  The article gives an overview of current advancements in the field of stem cell research, as well as perspectives for future clinical applications.

Stem cells are defined by their capacity to both self-renew and differentiate into multiple cell lines. Traditionally, they have been divided into two main groups based on their potential to differentiate. Pluripotent stem cells (embryonic) can differentiate into every cell of the body, whereas multipotent stem cells (adult) can differentiate into multiple, but not all, cell lineages.

In addition to the traditional stem cell classification, a new class of stem cells has recently been described—induced pluripotent stem cells—which are derived from genetically reprogrammed adult cells. These diverse cell populations will provide researchers and clinicians with an expanded armamentarium to treat diseased and dysfunctional organs.

Embryonic stem cells

  • are derived from the inner cell mass of the blastocyst and have the capacity to differentiate into all tissues of the body.
  • at least 225 human embryonic stem cell lines have been generated by researchers
  • the pluripotentiality and unlimited ability for self-renewal that make embryonic stem cells attractive for cell replacement therapy also simultaneously translates into unregulated differentiation and formation of teratomas and teratocarcinomas, especially in undifferentiated states
  • significant political and ethical hurdles that hinder further investigations of human embryonic stem cells

 

Adult stem cells

  1. avoid the ethical concerns regarding fetal tissue harvest
  2. well-studied adult stem cell population includes mesenchymal stem cells
  3. Mesenchymal stem cells have been isolated from bone marrow, umbilical cord blood, and adipose tissue.
  4. Adipose tissue–derived stem cells can be readily harvested during a minor liposuction procedure under local anesthesia.

Induced pluripotent stem cells

  1. Takahashi and Yamanaka published a landmark article in 2006 that defined a specific set of transcription factors capable of reverting differentiated cells back into a pluripotent state, thus creating “induced” pluripotent stem cells.
  2. It is widely accepted that mouse and human induced pluripotent stem cells closely resemble molecular and developmental features of blastocyst-derived embryonic stem cells

While the clinical potential for stem cell use is huge as noted in the article

Stem cell–based clinical trials are still in the early stages of development. In a preliminary case study, three patients were treated with autologous bone marrow stem cells seeded onto porous ceramic scaffolds for limb cortical defects ranging from 4 to 7 cm.  ………

In another case report, a 7-year-old girl with a critical-sized calvarial defect was successfully treated with cancellous iliac bone grafts in combination with autologous adipose tissue–derived stem cells.

In a case series, 20 patients with severe symptoms or irreversible functional skin damage due to radiotherapy were treated with autologous adipose tissue–derived stem cells delivered by computer-assisted injections.  …….

Interestingly, the first clinical phase I trial for utilizing adipose tissue–derived stem cells was carried out in patients with Crohn's disease. …..

In another phase I clinical trial, eight patients with Duchenne disease were treated with myogenic (muscle-derived CD133+) stem cells. ….

there is abuse of the term stem cell.  Stem cells facelifts are a marketing scheme (IMHO) which are promising results that haven’t been studied.

Stem Cell Face-Lifts?

Stem Cell Facelift: Fact or fiction?

The Newest Untested Fad:  Stem-Cell Facelifts

and from Dr. Thomas Fiala’s this blog post The "Stem Cell" facelift

But so far, we have no evidence - zip, zilch, nada - that there is any actual regenerative effect on skin when the turbo-charged fat is added to the face. We know you get more volume in the treated areas, so the treatment could be useful for those with a volume-depleted area, or those who want fuller cheeks - but that's about it.

Furthermore, under FDA rules, when stem cells get involved with fat transfers, the procedure falls under a whole new set of regulations. The fat and stem cell combo is now seen as a "biologic agent" by the FDA, and regulated as a drug. In the eyes of the FDA, stem cells and fat represent a non-approved drug. Investigational, yes - approved, no.

Interestingly, one of the spin-offs of this change to drug status is a change in whether physicians can advertise this process. They are no longer just advertising a procedure (the stem cell facelift), but they are doing direct-to-consumer marketing for a drug (the fat and stem-cell mixture) which has not yet been cleared by the FDA. And it's illegal to promote non-approved drugs.

Dr. Barry Eppley disagrees with the above stance in his post:  Stem Cell Facelifts - Science or Science Fiction?

Conversely, the hopeful part of a Stem Cell Facelift is that it is a perfectly natural procedure that has no harmful effects, an almost organic procedure if you will. It is all the patient’s own tissues and may exemplify the appealing concept of ‘heal thyself’. Because one’s own cells are being used (recycled?), it is not a procedure that requires FDA approval or that of any governing medical organization. (so don’t be misled that it is an FDA-approved procedure or technique) At the worst, one gets the benefit of fat grafting whether the stem cells really become alive or not. And the use of fat grafts to the face with our current appreciation of what happens as our face ages is a proven benefit.

However, in checking the FDA’s own website, I find that I would disagree with Dr. Eppley and agree with Dr. Fiala:  What are stem cells? How are they regulated?

Stem cells, like other medical products that are intended to treat, cure or prevent disease, generally require FDA approval before they can be marketed. At this time, there are no licensed stem cell treatments.

 

 

REFERENCES

Stem Cells; Behr, Björn; Ko, Sae Hee; Wong, Victor W.; Gurtner, Geoffrey C.; Longaker, Michael T.; Plastic & Reconstructive Surgery 126(4):1163-1171, October 2010; doi: 10.1097/PRS.0b013e3181ea42bb

1 comment:

Elaine Schattner, M.D. said...

I find it really interesting that stem cells are entering the domain of elective surgery. Some people I know who've had stem cell procedures don't realize that these are like blood products; if they're removed or derived from another human, they might harbor viruses and other potentially infectious organisms.