What is the deal with Platelet-Rich Plasma?

Recent treatments for joint pain due to cartilage damage are focusing in the area of less invasive solutions, and platelet-rich-plasma (PRP) is of interest to many clinicians and researchers alike. Platelets are particles in the human bloodstream that contain biological building blocks for tissues such as cartilage. The building blocks in platelets that are theorized to assist in healing include various growth factors and cytokines. The benefit of PRP are that it is a low cost and minimally invasive technique using the client’s own blood, however there is little known about the optimal method for preparing the PRP for the specific purpose of cartilage repair. It is important to find the most beneficial mixture because the growth factors and cytokines that will be released onto the client’s tissue could have very different and potentially detrimental results with only small changes in the concentrations. This particular study was conducted to investigate two different formulas, which have previously been shown to be beneficial, on human cartilage cells and the effects these different formulas will have on these cells.

In this study, blood from ten healthy male subjects was used to prepare two PRP solutions as well as a platelet poor solution (PPP) as a third comparison. The first platelet preparation (P-PRP) had a relatively low concentration of platelets and very few leukocytes. The second preparation (L-PRP) had high concentration of both platelets and leukocytes. The researchers tested these three preparations on cartilage taken from four male subjects all over the age of sixty-two with grade II osteoarthritis who were undergoing major knee surgery, meaning that they had pretty worn cartilage. The cartilage samples were broken down to extract the actual chondrocytes, which are the cells in charge of building new cartilage. Then the samples of chondrocytes were placed in the PRP formula for seven days. There were three preparations of each of the formulas; five, ten and twenty percent concentration of each PRP in order to assess various dose possibilities. Seven days was chosen because the clinical protocol includes a follow up injection at that time.

The growth of the chondrocytes was measured at one hour, three and seven days; genetic markers were measured at seven days; and hyaluronan and lubricin protein levels were also checked at the seven-day marker.

All three preparations increased growth of the chondrocytes, at all three times, but the P-PRP had a significantly increased cell growth on the seventh day. The genetic expressions tested also seemed to favor the P-PRP formula for stimulus of chondrocyte growth, however it appears that the L-PRP also promoted this growth, but through different pathways involving the leukocytes present in this formula. Surprisingly the PPP formula was also able to change the genetic expression similarly to the P-PRP samples, and it is theorized that simply having the plasma proteins and growth factors present in blood plasma will also positively affect cartilage repair. The L-PRP chondrocytes tended to secrete more hyaluronan, but both the L-PRP and the P-PRP caused similar secretion of lubricin. Both hyaluronan and lubricin are involved in joint lubrication.

The findings of this study suggest that more research is needed in this area, and there needs to be consideration taken into account as to the actual biological process that you want to be happening. This study has shown that different formulas of PRP and even PPP all seemed to provide positive effects on the cartilage, but through different pathways, indicating that some formulas could be more useful for different patients depending on their history.