Comparison of the effect of intra‐tendon applications of recombinant human platelet‐derived growth factor‐BB,platelet‐rich plasma,steroids in a rat achilles tendon collagenase model

This study compared the effect of intra‐tendon (IT) delivery of recombinant human platelet‐derived growth factor‐BB (rhPDGF‐BB), platelet‐rich plasma (PRP) and corticosteroids in a rat tendinopathy model. Seven days after collagenase induction of tendinopathy, a 30‐µl IT injection was administered. Treatments included: saline; 3 µg rhPDGF‐BB; 10 µg rhPDGF‐BB; PRP; and 300 µg triamcinolone acetonide (TCA). Outcomes were assessed 7 and 21 days after treatment. All groups exhibited good to excellent repair. Relative to saline, cell proliferation increased 65% in the 10 µg rhPDGF‐BB group and decreased 74% in the TCA group; inflammation decreased 65% in the TCA group. At 7 days, maximum load‐to‐failure was increased in the 3 µg rhPDGF‐BB group relative to saline, PRP, and TCA (p < 0.025). On day 21, maximum load‐to‐rupture was increased in the 10 µg rhPDGF‐BB group relative to saline, PRP, and TCA (p < 0.035) and in the 3 µg rhPDGF‐BB group compared to saline and TCA (p < 0.027). Stiffness in the 10 µg rhPDGF‐BB group was increased compared to saline, PRP, and TCA (p < 0.038). Histology demonstrated similar repair in all groups. PRP and TCA did not improve mechanical properties compared to saline. Injections of rhPDGF‐BB increased maximum load‐to‐failure (3 and 10 µg) and stiffness (10 µg) relative to controls and commonly used treatments. © 2013 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 32:145–150, 2014.     

Intraarticular injection autologous platelet‐rich plasma and bone marrow concentrate in a goat osteoarthritis model

To evaluate the effects of intraarticular injections of autologous platelet‐rich plasma (PRP) or bone marrow concentrate (BMC) on osteoarthritis (OA), 24 adult goats were equally divided into control (Ctrl), saline (NS), PRP, and BMC groups, and OA was induced by surgery in NS, PRP, and BMC groups. Autologous PRP and BMC were obtained from whole blood and bone marrow aspirates, respectively. The data revealed, platelets were increased in BMC by 1.8‐fold, monocytes by 5.6‐fold, TGF‐β1 by 7.7‐fold, and IGF‐1 by 3.6‐fold (p < 0.05), and platelets were increased in PRP by 2.9‐fold, and TGF‐β1 by 3.3‐fold (p < 0.05). From the sixth week post‐operation, saline, PRP, and BMC were administered by intraarticular injection once every 4 weeks, three consecutive times. After the animals were sacrificed, inflammatory cytokines in the synovial fluid was measured, and bone and cartilage degeneration progression was observed by macroscopy, histology, and immunohistochemistry. Compared with the NS group, the level of inflammatory cytokines was reduced in the PRP and BMC groups (p < 0.05). Histologically, delayed cartilage degeneration and higher levels of extracellular matrix (ECM) were observed in both PRP and BMC treated groups (p < 0.05). Furthermore, the BMC group showed greater cartilage protection and less ECM loss than the PRP group (p < 0.05). In summary, this study showed that intraarticular injection of autologous PRP and BMC has therapeutic efficacy in a goat osteoarthritis model, with the greater benefit in terms of cartilage protection being observed in the BMC‐treated group than PRP. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:2140–2146, 2018.

     

Endothelial cells incubated with platelet‐rich plasma express PDGF‐B and ICAM‐1 and induce bone marrow stromal cell migration

Platelet‐rich plasma (PRP) is used to accelerate bone repair through the growth factors released by platelets. The purpose of this study was to evaluate if PRP induce human umbilical vein endothelial cells (HUVEC) to express mRNA for osteogenic growth factors and stimulate the migration of bone marrow stromal cell (BMSC). The effects of PRP were compared to those induced by vascular endothelial growth factor‐A (VEGF‐A) or, as a negative control, by platelet poor plasma (PPP). After incubation with PRP, but not with PPP, HUVEC showed an increased expression of mRNA for platelet derived growth factor‐B (PDGF‐B), and this effect was not inhibited by an anti‐VEGF‐A antibody. The migration of BMSC was more stimulated by HUVEC incubated with PRP than by HUVEC incubated with low serum medium or PPP. Besides, PRP increased the expression of intercellular adhesion molecule‐1 (ICAM‐1) and osteoprotegerin, but did not affect the expression either of the receptor activator for nuclear factor κB ligand (RANKL) or of RANK. These findings support the hypothesis that PRP contribute to bone repair by favoring the pro‐osteogenic function of endothelial cells, including the recruitment of osteoblast precursors and the expression of adhesion molecules for monocyte/macrophages, while inhibiting their pro‐osteolytic properties. © 2009 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 27:1493–1498, 2009     

Epidermal growth factor vs platelet‐rich plasma: Activity against chronic wound microbiota

The objective was to evaluate Staphylococcus aureus and Pseudomonas aeruginosa colonisation of wounds treated with recombinant epidermal growth factor (EGF) and platelet‐rich plasma (PRP); to analyse the susceptibility profiles of S. aureus and P. aeruginosa isolates from wounds treated with EGF and PRP; and to describe the presence of infection in EGF‐treated and PRP‐treated wounds. Experimental study was performed using clinical specimens collected with swabs. Patients were treated with PRP and EGF in the outpatient clinic of a university hospital. Forty‐three isolates were obtained from 31 patients, 41.9% (13/31) of whom had been treated with EGF and 58.0% (18/31) with PRP. Ten of the 43 isolates were identified as S. aureus, 60.0% (6/10) of which were isolated from PRP‐treated wounds. Among the 33 P. aeruginosa isolates, 66.6% (22/33) were isolated from PRP‐treated wounds. Regarding antimicrobial susceptibility, only one strain isolated from an EGF‐treated wound was identified as methicillin‐resistant S. aureus (MRSA). Among the P. aeruginosa isolates, one obtained from a patient treated with EGF was multidrug‐resistant. Patients treated with EGF had no infections during the follow‐up period, and there was a significant difference between the 1st and 12th week in wound infection improvement in patients treated with PRP (P = .0078).     

Effects of age and platelet‐rich plasma on ACL cell viability and collagen gene expression

Platelet‐rich plasma (PRP) has shown in vivo potential to stimulate anterior cruciate ligament (ACL) healing at early time points in large animal models. However, in animal models, the healing potential of the ACL is dependent on animal age. In this study, we hypothesized that there are age‐dependent differences in ACL cell metabolism, collagen gene expression, and the ability of the cells to respond to growth factors in PRP. To test this hypothesis, ACL cells were obtained from skeletally immature, adolescent and adult pigs, and cultured in a collagen type I hydrogel with or without PRP for 14 days. When cultured in collagen‐only hydrogel, ACL cells from adult pigs had a 19% lower apoptotic rate as compared to immature pigs (p = 0.001) and a 25% higher cellular metabolic activity as compared to adolescent pigs (p = 0.006). The addition of PRP to the collagen hydrogel resulted in a significantly increased cellular metabolic activity, reduced apoptotic rate, and stimulation of collagen production in the cells from the immature and adolescent animals (p < 0.05 for all comparisons) but had less effect on adult cells. These findings suggest that skeletal maturity may influence ACL cells' metabolic activity, apoptosis, collagen production, and response to PRP. © 2011 Orthopaedic Research Society Published by Wiley Periodicals, Inc. J Orthop Res 30:79–85, 2012     

Increasing platelet concentration in platelet‐rich plasma inhibits anterior cruciate ligament cell function in three‐dimensional culture

Tissue engineering is one new strategy being developed to treat ACL ruptures. One such approach is bio‐enhanced ACL repair, where a suture repair is supplemented with a bio‐active scaffold containing platelets. However, the optimal concentration of platelets to stimulate ACL healing is not known. We hypothesized that increasing platelet concentrations in the scaffold would enhance critical cell behaviors. Porcine ACL fibroblasts were obtained from explant culture and suspended in platelet poor plasma (PPP), 1× platelet‐rich plasma (PRP), 3× PRP, 5× PRP, or phosphate buffered saline (PBS). The cell suspensions were cultured in a 3D collagen scaffold. Cellular metabolism (MTT assay), apoptosis (TUNEL assay), and gene expression for type I and type III collagen were measured. 1× PRP significantly outperformed 5× PRP in all parameters studied: Type I and III collagen gene expression, apoptosis prevention, and cell metabolism stimulation. ACL fibroblasts cultured with 1× PRP had the highest type I and type III collagen gene expression. 1× PRP and PPP groups had the highest cell metabolism and lowest apoptosis rates. Concentration of platelets had significant effects on the behavior of ACL fibroblasts; thus, it is an important parameter that should be specified in clinical or basic science studies. © 2013 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 32:291–295, 2014.     

Peripheral blood mononuclear cells enhance the anabolic effects of platelet‐rich plasma on anterior cruciate ligament fibroblasts

Use of platelet‐rich plasma (PRP) has shown promise in various orthopaedic applications, including treatment of anterior cruciate ligament (ACL) injuries. However, various components of blood, including peripheral blood mononuclear cells (PBMCs), are removed in the process of making PRP. It is yet unknown whether these PBMCs have a positive or negative effect on fibroblast behavior. To begin to define the effect of PBMCs on ACL fibroblasts, ACL fibroblasts were cultured on three‐dimensional collagen scaffolds for 14 days with and without PBMCs. ACL fibroblasts exposed to PBMCs showed increased type I and type III procollagen gene expression, collagen protein expression, and cell proliferation when the cells were cultured in the presence of platelets and plasma. However, addition of PBMCs to cells cultured without platelets had no effect. The increase in collagen gene and protein expression was accompanied by an increase in IL‐6 expression by the PBMCs with exposure to the platelets. Our results suggest that the interaction between platelets and PBMCs leads to an IL‐6 mediated increase in collagen expression by ACL fibroblasts. © 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 31:29–34, 2012     

Platelet‐rich plasma impairs osteoclast generation from human precursors of peripheral blood

Platelet‐rich plasma is used to accelerate bone repair for the release of osteogenic growth factors from activated platelets. To date, the effects on osteoclasts have been only scarcely investigated, even though these cells are crucial for bone remodeling. The aim of this research was the evaluation of the effects of thrombin‐activated platelets (PRP) on osteoclastogenesis from human blood precursors. We evaluated both the ability to influence osteoclast differentiation induced by the receptor activator of nuclear factor‐kappaB ligand (RANKL), and the ability to induce osteoclast differentiation without RANKL. In both assays, the incubation with PRP supernatant at 10% did not significantly affect the formation of tartrate‐resistant acid phosphatase (TRACP)‐positive multinucleated cells that were able to form the F‐actin ring. However, when PRP at 25 and 50% was added to the medium without RANKL, the generation of TRACP‐positive multinucleated cells was inhibited. PRP, even at 10%, reduced the osteoclast‐mediated bone collagen degradation, suggesting inhibition of osteoclast activation. Similarly, after incubation with PRP supernatant, calcitonin receptor mRNA was lower than the untreated samples. In conclusion, PRP at 10% interfered with the complete differentiation process of human osteoclast precursors. At higher concentration it impaired osteoclast formation also at an early stage of differentiation. © 2010 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 28:792–797, 2010     

Relationship of cytokine levels and clinical effect on platelet‐rich plasma‐treated lateral epicondylitis

Lateral epicondylitis (LE) is difficult to manage and can result in significant patient morbidity. Currently, the clinical use of platelet‐rich plasma (PRP) for painful tendons has received attention, but its efficacy remains controversial. This study aimed to investigate the clinical effects of PRP and its biological components. A total of 156 patients with LE were randomly divided into group 1, treated with a single injection of 2‐ml autologous PRP, and group 2, treated with a control received only physical therapy without injection. Both groups used a tennis elbow strap and performed stretching and strengthening exercises during 24 weeks’ follow‐up. Pain and functional improvements were assessed using the visual analog scale (VAS), Modified Mayo Clinic Performance Index for the elbow, and magnetic resonance imaging (MRI). White blood cell count, platelet count, and levels of platelet‐derived growth factor‐AB (PDGF‐AB), PDGF‐BB, transforming growth factor‐β (TGF‐β), vascular endothelial growth factor, epithelial growth factor, and interleukin‐1 β in PRP were measured and investigated for statistical correlation with the clinical score. At 24 weeks, all pain and functional variables, including VAS score, Mayo Clinic performance scores, and MRI grade, improved significantly in group 1 (p < 0.05). PDGF‐AB, PDGF‐BB, and TGF‐β levels were more significantly increased in PRP than in whole blood. TGF‐β level significantly correlated with Mayo Clinic performance score and MRI grade improvement. Thus, TGF‐β level in PRP is considered to play a pivotal role in tendon healing. These results may contribute to identifying the best protocol for PRP application in tendinopathies. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:913–920, 2018.

     

Efficacy of platelet‐rich plasma combined with allograft bone in the management of displaced intra‐articular calcaneal fractures: A prospective cohort study

To investigate whether platelet‐rich plasma (PRP) when used with allograft bone improves the management outcome of displaced intra‐articular calcaneal fractures. Over a 7‐year period, all displaced type III calcaneal fractures admitted in our department (276 fractures in 254 patients) were randomly divided into three groups according to the plan of management: autograft alone (n = 101), allograft combined with PRP (n = 85), or allograft alone (n = 90). Radiographic imaging and three‐dimensional computed tomography were used to assess the thalamic portion, Bohler's angle, the crucial angle of Gissane, and the height, width and length of the calcaneum. The American Orthopedic Foot and Ankle Society (AOFAS) ankle‐hind‐foot scoring system was used to evaluate the hind foot function at 12, 24, and 72 months postsurgery. At 12 months no significant difference existed in outcome amongst the treatment groups (p > 0.05). However, at 24 and 72 months the results of the autograft, and the allograft combined with PRP, were similar and both were significantly better than that of the allograft alone (p < 0.05). PRP augmented the favorable outcome of allografts in the management of displaced calcaneal fractures, and matched that of autograft used alone. The findings of this study thus support the clinical use of PRP in conjunction with allograft in the treatment of displaced intra‐articular calcaneal fractures. © 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 30:1570–1576, 2012     

Platelet‐rich plasma on calcium phosphate granules promotes metaphyseal bone healing in mini‐pigs

The role of platelet‐rich plasma (PRP) as a promoter of bone healing remains controversial. The aim of this study was to investigate the effect of PRP in combination with calcium phosphate granules (CPG) on bone defect healing in a metaphyseal long bone defect. A metaphyseal bone defect at the proximal tibia of 16 mini‐pigs was filled with CPG combined with autologous PRP or CPG solely (control group). The PRP showed 4.4‐fold more platelets compared to peripheral blood. Six weeks after surgery the radiological and histomorphometrical evaluations showed significantly more bone formation in the PRP group in the central area of the defect zone (p < 0.01) as well as the cortical defect zone (p < 0.04). Furthermore, the resorption rate of CPG was increased in animals who received PRP. Nevertheless there were only isolated instances of complete osseous bridging of the bone defects even in the PRP group. This study demonstrates that a PRP‐CPG composit promotes bone regeneration but does not lead to a solid fusion of a tibial defect in mini‐pigs. © 2010 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 28:1448–1455, 2010     

Autologous platelet‐derived growth factors (platelet‐rich plasma) as an adjunct to mucosal advancement flap in high cryptoglandular perianal fistulae: a pilot study

Aim The aim of this study was to explore autologous platelet‐rich plasma as an adjunct to the staged mucosal advancement flap in the treatment of perianal fistulae. Method Between February 2006 and May 2007, 10 patients with fistula tracts transversing from the middle‐third or upper part of the anal sphincter were treated for at least 3 months with noncutting setons prior to definitive closure by autologous platelet‐rich plasma as an adjunct to a mucosal advancement flap. Five patients smoked tobacco. Results The study group consisted of six women and four men with a median age of 44 (range 30–75) years and a median follow up of 26 (range 17–32) months. One (10%) patient had a recurrent fistula. No new continence disorders developed after definitive treatment in both groups. Conclusion Platelet‐rich plasma as an adjunct to a staged mucosal advancement flap for the treatment of perianal cryptoglandular fistulae is a promising treatment modality and seems to establish a high healing rate.     

In vivo study on the healing of bone defects treated with bone marrow stromal cells, platelet-rich plasma, and freeze-dried bone allografts, alone and in combination.

The repair of confined trabecular bone defects in rabbits treated by autologous bone marrow stromal cells (BMSC), platelet-rich plasma (PRP), freeze-dried bone allografts (FDBA) alone and in combination (BMSC + PRP; FDBA + BMSC; FDBA + PRP; FDBA + PRP + BMSC) was compared. A critical size defect was created in the distal part of the femurs of 48 adult rabbits. Histology and histomorphometry were used in the evaluation of healing at 2, 4, and 12 weeks after surgery. The healing rate (%) was calculated by measuring the residual bone defect area. Architecture of the newly formed bone was compared with that of bone at the same distal femur area of healthy rabbits. The defect healing rate was higher in PRP + BMSC, FDBA + PRP, FDBA + BMSC, and FDBA + PRP + BMSC treatments, while lower values were achieved with PRP treatment at all experimental times. The highest bone-healing rate at 2 weeks was achieved with FDBA + PRP + BMSC treatment, which resulted significantly different from PRP (p < 0.05) and BMSC (p < 0.05) treatments. At 4 weeks, the bone-healing rate increased except for PRP treatment. Finally, the bone-healing rate of FDBA + PRP, FDBA + BMSC, and FDBA + PRP + BMSC was significantly higher than that of PRP at 12 weeks (p < 0.05). At 12 weeks, significant differences still existed between PRP, BMSC, and FDBA groups and normal bone (p < 0.05). These results showed that the combination of FDBA, BMSC and PRP permitted an acceleration in bone healing and bone remodeling processes.     

Effects of platelet‐rich plasma on the quality of repair of mechanically induced core lesions in equine superficial digital flexor tendons: A placebo‐controlled experimental study

Tendon injuries are notorious for their slow and functionally inferior healing. Intratendinous application of platelet‐rich plasma (PRP) has been reported to stimulate the repair process of tendon injuries, but there is little conclusive evidence for its effectiveness. A placebo‐controlled experimental trial was performed to test the hypothesis that a single intratendinous PRP treatment enhances the quality of tendon repair, as evidenced by improved biochemical, biomechanical, and histological tissue properties. In six horses, tendon lesions were created surgically in the Superficial Digital Flexor Tendons (SDFT) of both front limbs, one of which was treated with PRP and the other with saline. After 24 weeks, the tendons were harvested for biochemical, biomechanical, and histological evaluations. Collagen, glycosaminoglycan, and DNA content (cellularity) was higher in PRP‐treated tendons (p = 0.039, 0.038, and 0.034, respectively). The repair tissue in the PRP group showed a higher strength at failure (p = 0.021) and Elastic Modulus (p = 0.019). Histologically, PRP‐treated tendons featured better organization of the collagen network (p = 0.031) and signs of increased metabolic activity (p = 0.031). It was concluded that PRP increases metabolic activity and seems to advance maturation of repair tissue over nontreated experimentally induced tendon lesions, which suggests that PRP might be beneficial in the treatment of clinical tendon injuries. © 2009 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 28:211–217, 2010     

Anti‐inflammatory effect of platelet‐rich plasma on nucleus pulposus cells with response of TNF‐α and IL‐1

The purpose of this study was to investigate the anti‐inflammatory effect of platelet‐rich plasma (PRP) with collagen matrix on human nucleus pulposus (NP) cell in response to pro‐inflammatory cytokines such as tumor necrosis factor‐alpha (TNF‐α) and interleukin‐1 (IL‐1). NP cells from human disks were cultured in a monolayer and maintained in the collagen matrix prior to the addition of recombinant human IL‐1 and TNF‐α. After applying IL‐1 and TNF‐α, PRP prepared by using a commercially available platelet concentration system was added. The response was investigated using real‐time PCR for mRNA expression of type II collagen, aggrecan, matrix metalloproteinase‐3 (MMP‐3), and cyclooxygenase‐2 (COX‐2). The combination of IL‐1β and TNF‐α led to decrease of matrix synthesis gene expression such as collagen type II and aggrecan and increase of the degradation gene expression of COX‐2 and MMP‐3, compared to the control. Consecutive PRP exposure significantly recovered the down‐regulated gene expression of collagen type II and aggrecan and significantly reduced the increased MMP‐3 and COX‐2 gene expression, compared to that of control groups with pro‐inflammatory cytokines. The administration of PRP with collagen matrix markedly suppressed cytokine‐induced pro‐inflammatory degrading enzymes and mediators in the NP cell. It also rescued gene expression concerning matrix synthesis, thereby stabilizing NP cell differentiation. © 2013 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 32:551–556, 2014.     

Systematic review of the efficacy of fat grafting and platelet‐rich plasma for wound healing

Adipose‐derived stem cells found in fat grafts may have significant healing properties. When fat is combined with autologous platelet‐rich plasma (PRP), there may be enhanced healing effects due to the pro‐angiogenic and anti‐inflammatory effects of PRP. This study aimed to evaluate the current evidence on fat grafting in combination with PRP for wound healing to establish the efficacy of this technique. A comprehensive search in the MEDLINE, EMBASE, CENTRAL, Science Citation Index, and Google Scholar databases (to March 2017) was conducted to identify studies on fat grafting and PRP for wound healing. Case series of less than 3 cases and studies only describing harvest technique were excluded. The database identified 571 articles, of which 3 articles that used a combination of fat and PRP for wound healing (1 RCT and 2 case series) were included in this review. A total of 69 wounds in 64 patients were treated with an average wound size of 36.32cm². Of these, 67% of wounds achieved complete healing. When reported, the mean time to healing was 7.5 weeks for those who underwent a single treatment. There were no significant complications in any patients. The combination of fat grafting and PRP may achieve adequate wound healing with relatively quick wound healing time compared with standard wound management options. However, evidence is extremely limited, and further studies are required to evaluate its efficacy for wound healing.     

Effect of platelet‐rich plasma on degeneration change of rotator cuff muscles: In vitro and in vivo evaluations

Atrophy with fatty degeneration is often seen in rotator cuff muscles with torn tendons. PRP has been reported to enhance tissue repair processes after tendon ruptures. However, the effect of PRP on atrophy and fatty degeneration of the muscle is not yet known. The aim of this study is to examine the effect of PRP on degeneration change of rotator cuff muscles in vitro and in vivo. A murine myogenic cell line and a rat rotator cuff tear model were used in this study and PRP was administrated into subacromial space which is widely used in clinical practice. In in vitro study, administration of PRP to C2C12 cells stimulated cell proliferation while inhibited both myogenic and adipogenic differentiation. In in vivo study, administration of PRP suppressed Oil Red‐O positive lipid droplet formation. The expression of adipogenic genes was also decreased by PRP administration. In conclusion, PRP promoted proliferation of myoblast cells, while inhibiting adipogenic differentiation of myoblast cells and suppressing fatty degeneration change in rat torn rotator cuff muscles. Further investigations are needed to determine the clinical applicability of the PRP. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1806–1815, 2017.