This insightful hair loss information was posted on our hair restoration forum by Dr. Jerry Cooley of Charlotte, NC who is a member of the Coalition of Independent Hair Restoration Physicians.
Graft survival and the use of platelet rich plasma in hair transplantation
Over the last year (2008), we have been testing the use of platelet – rich plasma (PRP) in hair transplant surgery. Our interest was stimulated by two previous hair restoration physicians, Carlos Uebel from Brazil and Joseph Greco from Florida, who reported improved healing and graft survival with use of PRP. Before discussing PRP, it is useful to take a look at the hair transplantation process in general.
Although we may sometimes take it for granted, it is quite amazing that hair follicles can be cut out of one area of the scalp and placed into an incision in another part of the scalp, and survive. Graft survival has been an interest of mine for many years, and I have written textbook chapters and given numerous lectures on this topic. We can divide these factors into three main categories: 1) follicle trauma 2) biochemical factors and 3) vascular factors (oxygenation / revascularization).
Follicle trauma refers to the transection, dehydration, and crushing that follicles can be subjected to during the surgery. Use of microscopes and follicular unit techniques minimizes transection. Keeping grafts moist throughout the process, especially graft placement, helps eliminate dehydration. Careful graft placement by an experienced placer will reduce crushing and damage to the graft. Most surgeons agree that reducing follicle trauma is the most important factor in determining graft survival.
Biochemical factors refer to the stress the hair follicles experience when they are kept out of the body for a period of time and then returned to the oxygenated graft bed. When tissue is outside the body, it undergoes “storage injury” due to cut off of oxygenated blood, lack of nutrients, and temperature/pH shifts. When this tissue is then put back in the body, it is re-exposed to oxygen, which sets off a spark of free radical production that may effect graft survival (“ischemia-reperfusion injury”). In our hair transplant clinic, we use tissue holding solutions which contain buffers, nutrients, and antioxidants which have been shown to reduce storage and ischemia-reperfusion injury. Most doctors use normal saline which lack these ingredients.
Vascular factors include the immediate post-operative oxygenation and successful revascularization of each graft. Unlike organ transplants where the transplanted organ is hooked up to a new blood supply, hair transplants are “free” grafts which are surgically implanted without re-attaching a new blood supply (because that would be impossible to do with hair follicles). Until this process is complete, the graft must survive by passively absorbing oxygen from the surrounding tissue. We have been using and testing a variety of techniques to â€˜prime the pump’ so to speak: topical hyperbaric oxygen, vasodilators, and angiogenesis stimulators. This is where platelet – rich plasma (PRP) comes in.
PRP was developed in the 1970’s but has only recently become popular in many fields of medicine. It is being widely used and studied in orthopedic surgery, dental/maxillofacial surgery, and regenerative medicine to name a few. Basically, platelets are isolated by first drawing the patient’s blood and spinning it down using special centrifuging techniques. A small fraction of plasma enriched with platelets is drawn from this and then reintroduced at the surgical site. Because the entire process is carried out with sterile, disposable instruments and devices, there is no chance for contamination.
How does applying PRP help transplanted hair? Remember that platelets are key players in the body’s wound healing mechanism. Whenever there is a wound (e.g. an incision to place a hair graft during hair replacement), the platelets are trapped in the clot and are activated to release various hair growth factors that stimulate the healing process. These naturally occurring growth factors include:
- PDGF (Platelet derived growth factor)
- TGF-a & b (Transforming growth factor alpha & beta)
- EGF (Epidermal growth factor)
- FGF (Fibroblast growth factor)
- Insulin-like growth factor (IGF)
- PDEGF (platelet derived epidermal growth factor)
- PDAF (platelet derived angiogenesis factor)
These factors stimulate new blood vessels to form (angiogenesis) and collagen to be produced. Cells are stimulated to divide and go into action surrounding the wound. In addition, white blood cells present in the area help eliminate bacteria in the area. PRP merely amplifies this naturally occurring wound healing process by providing increased numbers of platelets and white blood cells to the wound. It is important that the PRP be concentrated enough to have a therapeutic value and some techniques and devices in use by some physicians today may not accomplish this. Our system (Harvest SmartPrep) has been shown to produce at least 1.5 million platelets/1ml, well above the therapeutic threshold. This represents about a five-fold increase compared to the platelet count in circulating blood (for 10 cc of PRP). This is significantly greater than other commercially available devices
60 ml Process Volume
7 ml PRP 10 ml PRP
SmartPRep 1,3 7.6x 4.6x
Magellan2,3 5.1x 3.6x
COBE Angel4 4.3x 3.0x
Fresenius CATS1,3 3.4x
Biomet GPS 1 3.2x 2.3x
PPAI Sequire1 2.0x 1.4x
1Kevy, et al, Comparison of Methods for Point of Care Preparation of Autologous Platelet Gel, JECT, 2004; 36:28-35.
2Kevy, et al, Center for Blood Research; Presented at AMSECT – Hemostatis in Blood Management Meeting; April 2004
3Stammers, A.H., Trowbridge, C.C., et al, Establishment of a Quality Control Program for Platelet Gel Preparation: A Comparison of Four Commercial Devices – Society of Cardiovascular Anesthesiology Meeting: 9th Annual Update on Cardiopulmonary Bypass, March 2004
4Cobe Cardiovascular, Angel Whole Blood Separation, 2004 306700000 Rev A 10/04 5x increase in 10% of whole blood volume processed 5x in (0.10 x 60 ml) = 5x in 6 ml PRP
Both Uebel and Greco have found that coating the sites and grafts with PRP appears to speed up the healing process after a hair transplant. My experience over the last year has been the same. Redness and crusting are markedly less and everything just looks better quicker. Is the overall growth rate improved? Uebel and Greco have reported that this is the case. In general, I get excellent growth so it is hard to tell if there is a small benefit in terms of graft survival, but I think there is.
So why aren’t more hair transplant surgeons doing platelet rich plasma (PRP)? There is a cost factor: the centrifuge costs many thousands of dollars and with each case, hundreds of dollars of disposable supplies are used. Because PRP is still relatively new, many surgeons are not that familiar with it and there is a natural tendency to resist change, especially when it involves more time and money. More research needs to be done to provide convincing evidence of the benefits of PRP. Based on the impressive healing with PRP, and armed with an understanding of the documented benefit of PRP in other areas of medicine, I intend to keep testing it to further define its role in hair transplantation.
Dr. Jerry Cooley
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