The problem here is whole platelets removed from the body
In JW terminology, platelets are a primary component, not a fraction.
For JW patients, the acceptability of all forms of autologous transfusion is decided using recirculation as the litmus test.
A blood patch is acceptable only if the syringe remains connected to the vein throughout the procedure. Blood salvage and isovolemic hemodilution became acceptable to the JW community only after these procedures were modified to recirculate a small amount of the patient's blood.
I'd guess that PRP therapy acceptable to JWs, would probably require the collection apparatus to remain connected to the patient throughout the procedure (?)