Platelet-rich plasma (PRP) thought to hold potential beneficial effects in
Bone regeneration
Reduction in blood loss
Rapid tissue healing
Autologous product procured from patient up to 8 hours prior to use
Contains various growth factors act as
Chemotactic agents
Removal of tissue debris
Angiogenesis
Extracellular matrix deposition
Proliferation and differentiation
Described benefit in
Peridontal, craniofacial and spinal
Biological Properties of PRP
Platelet concentration 5 times higher than blood
Contain > 30 bioactive proteins
Fundamental role in tissue healing and haemostasis
Presynthesised secreted within 10-60 min
Synthesise and secrete factors for rest of life span
Unclear of role and interaction of these proteins
Biological activity of PRP
Activated by calcium and thrombin to release
Growth factors
Chemokines
Cytokines
Also contains other proteins
Fibrin, fibronectin, vitronectin, thrombospondin
These growth factors and proteins activate cells involved in
Soft tissue healing
Bone regeneration
Growth factors in PRP
PDGF- platelet derived growth factor
Angiogenesis, macrophage activation, fibroblast proliferation and chemotaxis, collagen synthesis, bone cell proliferation
TGF – transforming growth factor
Extracellular matrix production, fibroblast proliferation, type I collagen and fibronectin synthesis, bone matrix deposition, inhibition of osteoclasts and bone resorption
IGF – vascular endothelial growth factor
Chemotactic for fibroblasts, protein synthesis stimulation, proliferation and differentiation of osteoblasts
PDEF – platelet derived growth factor
Wound healing through epidermal regeneration, keratinocyte and dermal fibroblast stimulation
Growth factors in PRP
PDAF – platelet derived angiogensis factor
Induce vascularisation, upregulated by other cytokines and growth factors
PF-4 – platelet factor 4
Chemoattractant to neutrophils, fibroblasts, promotes coagulations by moderating heparin like molecules
EGF – epidermal growth factor
Epithelial proliferation and differentiation
VGEF – vascular endothelial growth factor
Vasculogenesis and angiogenesis, vasodilator and increased microvascular permeability
Platelet concentration and PRP
No agreement on concentration of platelets
Some authors advocate 10%
Others 1-5%
Different concentrations lead to variable effects on tissue regeneration
Affected by technique used to measure platelet count
Dependent on donor factors
Age, sex, platelet count of patient.
Higher platelet counts have higher growth factor concentrations
PRP preparation
May be prepared in
Laboratory
Operating theatre
Clinic
3 techniques
Gravitational platelet sequestration
table top centrifuge.
Blood is centrifuged to separate 3 layers:
RBC,
platelets
WBC, plasma.
PRP of 10% of blood volume can be collected after 12 min (eg 6ml PRP from 60ml blood).
RBC must be discarded.
Cell seperator
operate on full unit of blood – larger volumes.
RBC and platelet poor plasma (PPP) can be returned to patient.
Works on continuous centrifugation.
Plateletpheresis
selective filtration device.
No need for centrifuge.
Can increase platelet, growth factor and plasma protein concentration
PRP handling and application
Stable for 8 hours
Must be activated
Usually with topical bovine thrombin and CaCl
Must be used within 10 min of activation
PRP in vitro
Likely effects are synergistic
PRP shown to stimulate bone growth in rat bone marrow
Compared to individual growth factors having no effect
Improved cell proliferation in tendons cultured in PRP
Conflicting evidence over whether platelet need to be intact
PRP in animals
Conflicting evidence regarding effect
Improved bone healing and bone graft incorporation in rat skulls and mandibular reconstruction’s of goat
Shown to enhance bone healing significantly at 4 weeks
Improved healing in rat achilles, rat patella tendon and sheep supraspinatus tendon
No effect on PRP when used in association bone for skull defects that have been grafted
No effect on bone ingrowth at implant interface in rabbit femurs
Negative effect on demineralised bone in immunocompromised rats
PRP clinical studies
Quantity and delivery method are procedure specific
Most studies limited case series
Some evidence for increased bone consolidation in mandibular surgery
Some use in chronic ulcers and soft tissue defects
Study from Netherlands showed no benefit to PRP to NS in chronic achilles tendonitis
PRP in Orthopaedics
Minimal evidence supporting use in trauma and orthopaedic procedures
PRP in tendons
Some evidence for use in
Refractory lateral epicondylitis
Open achilles repair
Rotator cuff repairs
PRP in bone
Common to use with bone graft in mandible and cranium
PRP administered with good result in spinal fusion and osteogenesis distraction
PDGF and TGH-b measured in fracture haematomas of foot fractures
Non-union patients had no proteins found
PRP applied at revision operations had union at 8.5/52
Percutaneous application in non-union and delayed union when applied at <11 months resulted in union
PRP in arthroplasty
PRP when applied in TKR to exposed tissue and synovium and wound at closure
