Application of Platelet-Rich Plasma-Based Scaffolds in Soft and Hard Tissue Regeneration

Platelet-rich plasma (PRP) is a blood product with higher platelet concentrations than whole blood, offering controlled delivery of growth factors (GFs) for regenerative medicine. PRP plays pivotal roles in tissue restoration mechanisms, including angiogenesis, fibroblast proliferation, and extracellular matrix development, making it applicable across various regenerative medicine treatments. Despite promising results in different tissue injuries, challenges such as short half-life and rapid deactivation by proteases persist. To address these challenges, biomaterial-based delivery scaffolds, such as sponges or hydrogels, have been investigated. Current studies exhibit that PRP-loaded scaffolds fix these issues due to the sustained release of GFs. In this regard, given the widespread application of PRP in clinical studies, the use of PRP-loaded scaffolds has drawn significant consideration in tissue engineering (TE). Therefore, this review briefly introduces PRP as a rich origin of GFs, its classification, and preparation methods and discusses PRP applications in regenerative medicine. This study also emphasizes and reviews the latest research on the using scaffolds for PRP delivery in diverse fields of TE, including skin, bone, and cartilage repair.

Experimental Investigation of the Effect of Polydioxanone Plate and Platelet-Rich Plasma on Cartilage Regeneration

Objectives: This study aimed to investigate the effectiveness of polydioxanone (PDS) plate and platelet-rich plasma (PRP) on the regeneration of cartilage grafts, which are frequently used in nasal and septal surgery. Methods: Fifteen white New Zealand Albino-type female rabbits were used in the study. Our study was carried out on 4 different applications on each animal: cartilage only, cartilage+PRP, cartilage+PDS plate, and cartilage+PRP+PDS plate, and in 3 different periods: the first month, the second month, and the third month. Results: A significant difference was obtained between the groups using cartilage+PRP and cartilage+PRP+PDS only in the first month. When both application types were compared, a statistically significant decrease was found in the histopathological cartilage viability score after PDS use. In examining peripheral chondrocyte proliferation, a statistically significant difference was found only in the third-month comparison. When the group using only cartilage was compared with the group using cartilage+PDS, it was determined that peripheral chondrocyte proliferation was significantly reduced at the end of the third month with PDS. In evaluating fibrosis and foreign body reaction, a statistically significant increase was detected using a PDS plate. In histopathological cartilage viability score statistical analysis, a significant difference was obtained between the groups using cartilage+PRP and cartilage+PRP+PDS only in the first month. Degeneration in the cartilage structure was observed macroscopically in the specimens where the PDS plate was used. Shape change and cartilage deformation were observed in the PDS plate specimens. Conclusions: When the results were examined, this observation coincided with the statistically significant increase in foreign body reaction and fibrosis in the PDS plate groups. However, these results contradicted our hypothesis before the study and the information in the literature. Our results will help provide preliminary information and guidance for future studies and offer a different perspective.

Achieving Nasal Septal Cartilage In Situ Regeneration: Focus on Cartilage Progenitor Cells

The nasal septal cartilage plays an important role in preventing the collapse of the nasal bones and maintaining the appearance of the nose. In the context of inherent difficulties regarding septal cartilage repair and the shortage of cartilage graft resources for regeneration, tissue engineering, especially the in situ strategy based on scaffolds, has become a new prospect and become one of the most promising approaches. Given that it is difficult for chondrocytes to achieve directional migration and secrete matrix components to participate in tissue repair after cartilage injury, cartilage progenitor cells (CPCs), with great migratory ability and stem cell characteristics, have caught the attention of researchers and brought hope for nasal septal cartilage in situ regeneration. In this review, we first summarized the distribution, characteristics, isolation, and culture methods of nasal septal CPCs. Subsequently, we described the roles of migratory CPCs in cartilage regeneration. Finally, we reviewed the existing studies on CPCs-based cartilage tissue engineering and summarized the strategies for promoting the migration and chondrogenesis of CPCs so as to provide ideas for achieving nasal septal cartilage in situ regeneration.

Office-Based Intraosseous Infiltrations of PRGF as an Effective Treatment for Knee Osteoarthritis: A Retrospective Observational Clinical Study

The aim of this study was to explore and assess office-based ultrasound-guided intraosseous and intra-articular infiltrations of plasma rich in growth factors (PRGF) in patients with moderate and severe knee osteoarthritis (KOA). Seventy-nine patients (30 women and 49 men) with grade 3-4 KOA according to the Kellgren-Lawrence classification participated in the study. All patients were treated with a minimally invasive technique using local anesthesia WALANT (wide-awake local anesthesia no tourniquet) in the ambulatory setting. A PRGF intra-articular infiltration and two intraosseous infiltrations in the tibial plateau and femoral condyle were performed weekly for a total of three sessions. The evaluation of the results was carried out using knee injury and osteoarthritis outcome score (KOOS) at baseline and post-treatment. After a follow-up period of 11 months (median) [interquartile range, 7-14], all the KOOS domains showed statistically significant improvement (p < 0.001). Moreover, 88% of the patients showed a pain reduction of at least 10 points (minimally clinically important improvement) from pre- to post-treatment. Our retrospective study using the in-office procedure of ultrasound-guided combination of intra-articular and intraosseous infiltrations of PRGF is a safe and efficacious approach for the treatment of grade 3-4 knee osteoarthritis.

A Biodegradable Polymeric Matrix for the Repair of Annulus Fibrosus Defects in Intervertebral Discs

BACKGROUND

Tissue defects in the annulus fibrosus (AF) due to intervertebral disc (IVD) degeneration or after nucleodiscectomy have little self-healing capacity. To prevent progressive degeneration of the IVD, the AF must be repaired. Biological closure has not yet been achieved and is a challenge for the research community. In this study, a scaffold made of absorbable poly (glycolic acid) (PGA) and hyaluronan (HA) that exhibit excellent biocompatibility and cell colonization properties was used to repair AF defects in an ovine model.

METHODS

A partial resection was performed in AF in L3/4 or L4/5 of 10 sheep and PGA-HA scaffolds were implanted on the defects (n = 5), while defects in the control group were left untreated (n = 5). Three months post-operation, the lumbar discs were sectioned and stained with hematoxylin and eosin and safranin-O/fast-green. Histological features including proteoglycan content, annular structure, cellular morphology, blood vessel ingrowth and tear/cleft formation were scored using a modified scoring scheme by 3 investigators and evaluated by a pathologist independently.

RESULTS

The treated AF exhibited significantly enhanced repair tissue structure with signs of proteoglycan formation compared to the untreated group. The median scores were 4.3 for the treated and 9.8 for the untreated group. Cystic degeneration, perivascular infiltration, inflammation and necrosis were only present in the untreated group. Blood vessel ingrowth and tear/cleft formation were increased, though not significant, in the untreated group while cell morphology was comparable in both groups.

CONCLUSION

PGA-HA scaffolds used for AF closure support repair tissue formation in an ovine lumbar disc defect model.

Platelet-rich plasma-hyaluronic acid/chondrotin sulfate/carboxymethyl chitosan hydrogel for cartilage regeneration

In this study, the chondrogenic potential of hyaluronic acid/chondrotin sulfate/carboxymethyl chitosan hydrogels with adipose-derived mesenchymal stem cells (ADMSCs) was evaluated. Here, hyaluronic acid, chondrotin sulfate, and carboxymethyl chitosan were used as the substrate for cartilage tissue engineering in which the hydrogel is formed due to electrostatic and hydrogen bonds through mixing the polymers. Because of the instability of this hydrogel in the biological environment, 1-ethyl-3-(3-dimethylaminopropyl-carbodiimide hydrochloride/N-hydroxy-succinimide was used as a crosslinker to increase the hydrogel stability. The hydrogels showed reasonable stability due to the combined effect of self-crosslinking and chemical crosslinking. The cells were treated with the prepared hydrogel samples for 14 and 21 days in nondifferentiation medium for evaluation of the cellular behavior of ADMSCs. Gene expression evaluation was performed, and expression of specific genes involved in differentiation was shown in the crosslinked hydrogel with platelet-rich plasma (PRP) (H-EN-P) had increased the gene expression levels. Quantification of immunofluorescence intensity indicated the high level of expression of SOX9 in H-EN-P hydrogel. Based on the results, we confirmed that the presence of PRP and the similarity of the hydrogel constituents to the cartilage extracellular matrix could have positive effects on the differentiation of the cells, which is favorable for cartilage tissue engineering approaches.

Intra-articular Pure Platelet-Rich Plasma Combined With Open-Wedge High Tibial Osteotomy Improves Clinical Outcomes and Minimal Joint Space Width Compared With High Tibial Osteotomy Alone in Knee Osteoarthritis: A Prospective Study

PURPOSE

To compare the clinical efficacy of the patients with medial compartment knee osteoarthritis who underwent either opening-wedge high tibial osteotomy alone (HTO) or simultaneous HTO and pure platelet-rich plasma therapy (HTO+P-PRP).

METHODS

Eighty patients were divided into 2 groups randomly, the HTO-alone group (n = 41) and the HTO+P-PRP group (n = 39). Patients were matched for preoperative age, sex, and body mass index. The outcomes studied included visual analogue scale (VAS) score, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and Lysholm score. The minimum width of medial knee joint (MJSW), medial proximal tibial angle (MPTA), femoral tibial angle (FTA), and weightbearing line (WBL) were measured preoperatively, immediately postoperatively, and 1, 6, 12, and 24 months postoperatively. Paired t test and chi-squared test were used for statistical analysis.

RESULTS

All patients were followed up at 1, 6, 12, and 24 months postoperatively. At 1, 6, and 12 months, pain and function scores in the HTO+P-PRP group were better than those in the HTO-alone group, especially at 6 months in Lysholm score (HTO alone, 72.5 ± 10.6; HTO+P-PRP, 83.1 ± 14.7; P = .003, 95% CI -14.13 to -10.42) and WOMAC (HTO alone, 90.3 ± 11.9; HTO+P-PRP, 75.6 ± 15.4; P < .001, 95% CI 13.36 to 20.11). For both groups, no difference was found preoperatively (HTO alone, varus 3.5 ± 3.9; HTO+P-PRP, varus 4.1 ± 4.0; P = .898) or postoperatively (HTO alone, valgus 6.7 ± 4.5; HTO+P-PRP, valgus 7.7 ± 2.3; P = .768) in FTA or WBL. The increase of the MJSW in the HTO+P-PRP group was significantly greater than that in the HTO-alone group during the first year, especially at 6 months (HTO alone, 3.8 ± 1.2 mm; HTO+P-PRP, 4.6 ± 1.1 mm; P = .001, 95% CI -1.27 to -0.35).

CONCLUSIONS

Compared with HTO alone, HTO combined with intra-articular P-PRP improved the minimum medial knee joint space width during the first year postoperatively. Clinically, a higher proportion of patients in the HTO+P-PRP group exceeded the minimal clinically important difference (MCID) in the first year, especially at 6 months in Lysholm score (HTO alone, 65.9%; HTO+P-PRP, 97.4%) and WOMAC (HTO alone, 82.9%; HTO+P-PRP, 100.0%).

LEVEL OF EVIDENCE

2, prospective comparative study.

Effect of Platelet-Derived Concentrated Growth Factor on Single-Layer, Multi-Layer, and Crushed Onlay Cartilage Grafts

BACKGROUND

The main concern with utilizing cartilage grafts to achieve structural integrity and volume restoration is the loss of volume over time and their unpredictable viability. Preservation of the volume of cartilage grafts is necessary to ensure their long-term success.

OBJECTIVES

The main aim of this study was to investigate the effect of concentrated growth factor (CGF) sheet on single-layer, multi-layer, and crushed block cartilage grafts.

METHODS

Cartilage grafts obtained from the ears of rabbits were prepared in 3 different forms: single-layer, triple-layer, and crushed. After measuring the weight and thickness of the cartilage grafts, the grafts in the experimental group were wrapped with the prepared autologous CGF. These cartilage grafts were placed in subcutaneous pouches created on the backs of the rabbits. After 4 months, the rabbits were killed. The weight and thickness of the cartilage grafts were measured and the cartilage viability and peripheral changes were examined microscopically.

RESULTS

The percentage changes in the weights and thicknesses of the single-layer, multi-layer, and crushed cartilage grafts wrapped with CGF were found to be statistically significantly lower than in the control group. When the cartilage viability and changes in peripheral tissue were evaluated, CGF-wrapped cartilage groups did not achieve statistically significantly better scores than the untreated control groups.

CONCLUSIONS

In cases planned to receive a block cartilage graft, especially if graft resorption is not desired or should be minimized, wrapping the graft with autologous CGF is a feasible option.

Intra-Articular Platelet-Rich Plasma Combined With Hyaluronic Acid Injection for Knee Osteoarthritis Is Superior to Platelet-Rich Plasma or Hyaluronic Acid Alone in Inhibiting Inflammation and Improving Pain and Function

PURPOSE

To evaluate the effectiveness and explore the therapeutic mechanisms of platelet-rich plasma (PRP) combined with hyaluronic acid (HA) as a treatment for knee osteoarthritis (KOA).

METHODS

In total, 122 knees were randomly divided into HA (34 knees), PRP (40 knees), and PRP+HA (48 knees) groups. Platelet densities in whole blood and PRP were examined using Wright-Giemsa staining. Visual analogue scale, Lequesne, Western Ontario and McMaster Universities Osteoarthritis Index, Lysholm scores, and postoperative complications were evaluated. High-frequency color Doppler imaging was used to observe the synovium and cartilage. Enzyme-linked immunosorbent assays were used to quantify interleukin-1β, tumor necrosis factor-α, matrix metalloproteinase-3, and tissue inhibitor of metalloproteinase-1 levels in synovial fluid.

RESULTS

The platelet density in PRP was 5.13-times that in whole blood (P = .002). At 24 months, pain and function scores in the PRP+HA group were better than those in the HA-alone and PRP-alone groups (P_pain = .000; P_function = .000). At 6 and 12 months, synovial hyperplasia in the PRP and PRP+HA groups was improved (P < .05). After 6 and 12 months, the synovial peak systolic velocity, synovial end-diastolic velocity, systolic/diastolic ratio, and resistance index were improved in the PRP+HA group (P < .05). Complications were greatest in the PRP group (P = .008). After 6 and 12 months, interleukin-1β, tumor necrosis factor-α, matrix metalloproteinase-3, and tissue inhibitor of metalloproteinase-1 in the PRP and PRP+HA groups decreased (P < .05), with more apparent inhibition in the PRP+HA group (P < .05).

CONCLUSIONS

PRP combined with HA is more effective than PRP or HA alone at inhibiting synovial inflammation and can effectively improve pain and function and reduce adverse reactions. Its mechanism involves changes in the synovium and cytokine content.

LEVEL OF EVIDENCE

Level II, Prospective cohort study.

Platelet-Rich Plasma Therapy in the Treatment of Diseases Associated with Orthopedic Injuries

Platelet-rich plasma (PRP) is an autologous platelet concentrate prepared from the whole blood that is activated to release growth factors (GFs) and cytokines and has been shown to have the potential capacity to reduce inflammation and improve tissue anabolism for regeneration. The use of PRP provides a potential for repair due to its abundant GFs and cytokines, which are key in initiating and modulating regenerative microenvironments for soft and hard tissues. Among outpatients, orthopedic injuries are common and include bone defects, ligament injury, enthesopathy, musculoskeletal injury, peripheral nerve injury, chronic nonhealing wounds, articular cartilage lesions, and osteoarthritis, which are caused by trauma, sport-related or other types of trauma, or tumor resection. Surgical intervention is often required to treat these injuries. However, for numerous reasons regarding limited regeneration capacity and insufficient blood supply of the defect region, these treatments commonly result in unsatisfactory outcomes, and follow-up treatment is challenging. The aim of the present review is to explore future research in the field of PRP therapy in the treatment of diseases associated with orthopedic injuries. Impact statement In recent years, platelet-rich plasma (PRP) has become widely used in the treatment of diseases associated with orthopedic injuries, and the results of numerous studies are encouraging. Due to diseases associated with orthopedic injuries being common in clinics, as a conservative treatment, more and more doctors and patients are more likely to accept PRP. Importantly, PRP is a biological product of autologous blood that is obtained by a centrifugation procedure to enrich platelets from whole blood, resulting in few complications, such as negligible immunogenicity from an autologous source, and it is also simple to produce through an efficient and cost-effective method in a sterile environment. However, the applicability, advantages, and disadvantages of PRP therapy have not yet been fully elucidated. The aim of the present review is to explore future research in the field of PRP therapy in the treatment of diseases associated with orthopedic injuries, as well as to provide references for clinics.

Autologous Platelet Lysate Does Not Enhance Chondrogenic Differentiation of Equine Bone Marrow-Derived Mesenchymal Stromal Cells Despite Increased TGF-β1 Concentration

Bone marrow-derived mesenchymal stromal cells (BM-MSCs) are being investigated for their potential in the treatment of musculoskeletal injuries, including tendon and ligament lesions, and cartilage lesions. Culture expansion of cells has traditionally been performed in medium supplemented with fetal bovine serum (FBS), however, concerns regarding the antigenicity and potential viral or prion contamination of FBS have prompted interest in alternative medium supplements. Platelet lysate (PL) contains elevated concentrations of growth factors, including transforming growth factor-β (TGF-β), platelet-derived growth factors, and fibroblast growth factor, released from the α-granules of platelets; therefore, PL could be an ideal medium supplement. The effect of PL on mesenchymal stromal cell (MSC) growth and differentiation has not been fully elucidated. We hypothesized that PL medium would contain significantly higher amounts of TGF-β1 than FBS medium and would be associated with enhanced osteogenic and chondrogenic differentiation. MSCs were isolated from bone marrow collected from five adult horses. Cells were cultured in traditional medium supplemented with FBS or in medium supplemented with fibrinogen depleted-PL (FD-PL). Immunophenotyping was performed using flow cytometry. Trilineage differentiation was assessed through histology and gene expression analysis using quantitative reverse transcription-polymerase chain reaction. TGF-β1 was quantified in both medium types. The immunophenotypes of BM-MSCs cultured in FBS and FD-PL medium were similar with both culture types containing cells positive for stromal cell markers [cluster of differentiation 29 (CD29), CD44, CD90, CD105, and major histocompatibility complex I (MHCI)] and negative for exclusion markers (CD45, CD79α, and MHCII). Despite significantly higher TGF-β1 concentration in FD-PL medium, chondrogenic and osteogenic differentiation were not significantly different between FBS and FD-PL supplemented cultures. PL is an appropriate alternative medium supplement for the culture of equine BM-MSCs up to passage 3. However, despite increased TGF-β1 concentration in FD-PL medium, significant changes in chondrogenic differentiation compared with FBS medium should not be expected.

PRP and BMAC for Musculoskeletal Conditions via Biomaterial Carriers

Platelet-rich plasma (PRP) and bone marrow aspirate concentrate (BMAC) are orthobiologic therapies considered as an alternative to the current therapies for muscle, bone and cartilage. Different formulations of biomaterials have been used as carriers for PRP and BMAC in order to increase regenerative processes. The most common biomaterials utilized in conjunction with PRP and BMAC clinical trials are organic scaffolds and natural or synthetic polymers. This review will cover the combinatorial strategies of biomaterial carriers with PRP and BMAC for musculoskeletal conditions (MsCs) repair and regeneration in clinical trials. The main objective is to review the therapeutic use of PRP and BMAC as a treatment option for muscle, bone and cartilage injuries.

Platelet-rich gel-incorporated silk scaffold promotes meniscus regeneration in a rabbit total meniscectomy model

Aim: To investigate whether platelet-rich gel (PRG) incorporation could promote meniscal regeneration of the silk scaffold. Materials & methods: A PRG-incorporated silk sponge was fabricated for reconstruction of the meniscus in a rabbit meniscectomy model. Subsequently, characterization of the scaffold, as well as the in vitro cytocompatibility and in vivo function was evaluated. Results: Our results showed that the PRG-incorporated silk scaffold provided a sustained release of TGF-β1 over 1 week. The PRG enhanced the cytocompatibility in vitro and cell infiltration in vivo of the silk sponge. Meanwhile, the implantation of the composite in situ ameliorated the cartilage degeneration in knee at 3 months. Conclusion: These findings indicated that PRG-incorporated silk scaffold could promote functional regeneration of the meniscus and effectively prevented subsequent osteoarthritis after meniscectomy.

Meniscus-shaped cell-free polyglycolic acid scaffold for meniscal repair in a sheep model

Since loss of meniscus is correlated with an increasing risk for osteoarthritis, meniscal scaffolds are proposed as new strategies. Development of a suitable scaffold has to take into account differing meniscus thickness, exposure to compressive and tensile forces combined with high porosity and biocompatibility of the material. After physical testing of three flat scaffolds composed of different modified polyglycolic acid (PGA) fibers, a three-dimensional meniscus-shaped PGA-hyaluronan implant was generated. Micro-computed tomography showed 90% porosity in the outer area with 50% in the inner area of the implant. Biocompatibility and expression of meniscus typical cartilaginous genes were shown for human meniscus cells cultivated in the implant with 10% human serum or 5% platelet-rich plasma for 14 days in vitro. The proof-of-concept study in sheep demonstrated proteoglycan- and collagen type I-rich repair tissue formation in partial meniscectomy combined with a meniscus-shaped PGA-hyaluronan implant after 6 months. In contrast, the control showed nearly no repair tissue formation. Thus, meniscus-shaped PGA-hyaluronan implants might be a suitable therapeutic approach to support repair tissue formation in partial meniscectomy.

An injectable platelet lysate-hyaluronic acid hydrogel supports cellular activities and induces chondrogenesis of encapsulated mesenchymal stem cells

Developing scaffolds that can provide cells and biological cues simultaneously in the defect site is of interest in tissue engineering field. In this study, platelet lysate (PL) as an autologous and inexpensive source of growth factors was incorporated into a cell-laden injectable hyaluronic acid-tyramine (HA-TA) hydrogel. Subsequently, the effect of platelet lysate on cell attachment, viability and differentiation of human mesenchymal stem cell (hMSCs) toward chondrocytes was investigated. HA-TA conjugates having a degree of substitution of 20 TA moieties per 100 disaccharide units were prepared and crosslinked in the presence of horseradish peroxidase and low concentrations of hydrogen peroxide. The storage moduli of the gels ranged from 500 to 2000 Pa and increased with increasing polymer concentration. In contrast to a retained round shape of the cells when using pure HA-TA hydrogel, the hMSCs attached and spread out in PL enriched matrix. The enrichment of hMSCs laden HA-TA hydrogels with PL induced a cartilage like extra cellular matrix deposition in vitro. The hMSCs increasingly deposited collagen type II and proteoglycans over time. The deposition of the new extracellular matrix (ECM) is simultaneous with gel degradation and resulted ultimately in the formation of a tough dense matrix. These findings demonstrate the potential of injectable HA-TA-PL hydrogel as a cell delivery system for cartilage regeneration. STATEMENT OF SIGNIFICANCE: Cartilage tissue has limited ability to self-repair because of its avascular nature. To have an efficient cartilage tissue regeneration, we combined platelet lysate (PL), as an autologous and inexpensive source of growth factors, with an injectable hyaluronic acid tyramine (HA-TA) hydrogel scaffold. Platelet lysate had a vital role in supporting human mesenchymal stem cells (hMSCs) activities, like cell attachment, viability and proliferation in the 3D hydrogel structure. Also, the hMSCs encapsulated HA-TA induced hyaline cartilage generation when placed in chondrogenic differentiation medium. This study introduces a new system for cartilage tissue engineering, which can be injected in a minimally invasive manner and is rich with patient's own growth factors and biological cues.

A 24-month follow-up after treatment of hallux rigidus with resection arthroplasty in combination with a resorbable polymer-based implant and platelet-rich plasma

BACKGROUND

Aim of this study was to analyze the clinical outcome after treatment of hallux rigidus with implantation of a resorbable polymer-based implant immersed with autologous platelet-rich plasma (PRP).

METHODS

Forty-five patients with hallux rigidus were treated with three-stage resection arthroplasty and subsequent covering of the metatarsal head with a polyglycolic acid-hyaluronan implant immersed with autologous PRP. Patients were clinically assessed using the AOFAS rating scale preoperatively and at 12 and 24 month follow-up. Alignment and range of motion in the metatarsophalangeal joint was measured using a goniometer.

RESULTS

The AOFAS rating scale and ROM showed significant (p<.01) improvement in all subcategories one and two years after surgery compared to the preoperative situation.

CONCLUSIONS

Covering of the metatarsal head after resection arthroplasty with the PGA-hyaluronan implant immersed with autologous PRP is safe and leads to a notable improvement of the symptoms in patients with hallux rigidus.

Current concepts in treatment of early knee osteoarthritis and osteochondral lesions; the role of biological augmentations

Early knee osteoarthritis and chondral lesions are a common cause of disability in younger patients. Surgical options, such as microfractures, ACI and OAT, provide good, but not fully satisfying, outcomes. Recent advance in biological knowledge introduced two different methodological approaches of delivering growth factors and stem cells into the articular environment. Platelet-Rich Plasma and Mesenchimal Stem Cells are supposed to change the way to approach early knee osteoarthritis and chondral lesions, though their indications and limits are yet to be determined.

Current concepts in treatment of early knee osteoarthritis and osteochondral lesions; the role of biological augmentations

Early knee osteoarthritis and chondral lesions are a common cause of disability in younger patients. Surgical options, such as microfractures, ACI and OAT, provide good, but not fully satisfying, outcomes. Recent advance in biological knowledge introduced two different methodological approaches of delivering growth factors and stem cells into the articular environment. Platelet-Rich Plasma and Mesenchimal Stem Cells are supposed to change the way to approach early knee osteoarthritis and chondral lesions, though their indications and limits are yet to be determined.

Human platelet-rich plasma improves the nesting and differentiation of human chondrocytes cultured in stabilized porous chitosan scaffolds

The clinical management of large-size cartilage lesions is difficult due to the limited regenerative ability of the cartilage. Different biomaterials have been used to develop tissue engineering substitutes for cartilage repair, including chitosan alone or in combination with growth factors to improve its chondrogenic properties. The main objective of this investigation was to evaluate the benefits of combining activated platelet-rich plasma with a stabilized porous chitosan scaffold for cartilage regeneration. To achieve this purpose, stabilized porous chitosan scaffolds were prepared using freeze gelation and combined with activated platelet-rich plasma. Human primary articular chondrocytes were isolated and cultured in stabilized porous chitosan scaffolds with and without combination to activated platelet-rich plasma. Scanning electron microscopy was used for the morphological characterization of the resulting scaffolds. Cell counts were performed in hematoxylin and eosin–stained sections, and type I and II collagen expression was evaluated using immunohistochemistry. Significant increase in cell number in activated platelet-rich plasma/stabilized porous chitosan was found compared with stabilized porous chitosan scaffolds. Chondrocytes grown on stabilized porous chitosan expressed high levels of type I collagen but type II was not detectable, whereas cells grown on activated platelet rich plasma/stabilized porous chitosan scaffolds expressed high levels of type II collagen and type I was almost undetectable. In summary, activated platelet-rich plasma increases nesting and induces the differentiation of chondrocytes cultured on stabilized porous chitosan scaffolds.

Intra-articular bone marrow concentrate injection protocol: short-term efficacy in osteoarthritis

AIM

Evaluate intra-articular injection of bone marrow concentrate (BMC), followed by platelet-rich plasma (PRP) injection at 8 weeks follow-up in moderate/severe osteoarthritis.

DESIGN

Single center, retrospective Case Series (n = 125).

METHODS

Bone marrow was aspirated/concentrated using a standardized technique. Patients received a single intra-articular injection of BMC, with follow-up injection of PRP at 8 weeks.

RESULTS

Median absolute pain reduction in all joints was five points (71.4%) on visual analog scale. Median patient satisfaction was 9.0/10, while 91.7% indicated that they would repeat the procedure and 94% said that they would recommend the procedure to a friend.

CONCLUSION

Intra-articular injection of BMC, followed by a PRP injection, can provide short-term benefits in moderate-to-severe osteoarthritis.

Biologic Treatments for Sports Injuries II Think Tank-Current Concepts, Future Research, and Barriers to Advancement, Part 3: Articular Cartilage

Focal chondral defects of the articular surface are a common occurrence in the field of orthopaedics. These isolated cartilage injuries, if not repaired surgically with restoration of articular congruency, may have a high rate of progression to posttraumatic osteoarthritis, resulting in significant morbidity and loss of function in the young, active patient. Both isolated and global joint disease are a difficult entity to treat in the clinical setting given the high amount of stress on weightbearing joints and the limited healing potential of native articular cartilage. Recently, clinical interest has focused on the use of biologically active compounds and surgical techniques to regenerate native cartilage to the articular surface, with the goal of restoring normal joint health and overall function. This article presents a review of the current biologic therapies, as discussed at the 2015 American Orthopaedic Society for Sports Medicine (AOSSM) Biologics Think Tank, that are used in the treatment of focal cartilage deficiencies. For each of these emerging therapies, the theories for application, the present clinical evidence, and specific areas for future research are explored, with focus on the barriers currently faced by clinicians in advancing the success of these therapies in the clinical setting.

A new strategy to tackle severe knee osteoarthritis: Combination of intra-articular and intraosseous injections of Platelet Rich Plasma

INTRODUCTION

Knee osteoarthritis (KOA) is a mechanically induced, cytokine and enzyme-mediated disorder involving all the joint tissue of the knee. Rebuilding a physiological-homeostatic network at the tissue level following knee organ failure, such as in severe KOA, is a daunting task with therapeutic targets encompassing the articular cartilage, synovium and subchondral bone. Intraarticular infiltration of plasma rich in growth factors (PRP) has emerged as a promising symptomatic approach, although it is insufficient to reach the subchondral bone.

AREAS COVERED

This review addresses current molecular and cellular data in joint homeostasis and osteoarthritis pathophysiology. In particular, it focuses on changes that subchondral bone undergoes in knee osteoarthritis and evaluates recent observations on the crosstalk among articular cartilage, subchondral bone and synovial membrane. In addition, we review some mechanistic aspects that have been proposed and provide the rationale for using PRP intraosseously in KOA.

EXPERT OPINION

The knee joint is a paradigm of autonomy and connectedness of its anatomical structures and tissues from which it is made. We propose an innovative approach to the treatment of severe knee osteoarthritis consisting of a combination of intraarticular and intraosseous infiltrations of PRP, which might offer a new therapeutic tool in KOA therapy.

Platelet-Rich Blood Derivatives for Stem Cell-Based Tissue Engineering and Regeneration

Platelet rich blood derivatives have been widely used in different fields of medicine and stem cell based tissue engineering. They represent natural cocktails of autologous growth factor, which could provide an alternative for recombinant protein based approaches. Platelet rich blood derivatives, such as platelet rich plasma, have consistently shown to potentiate stem cell proliferation, migration, and differentiation. Here, we review the spectrum of platelet rich blood derivatives, discuss their current applications in tissue engineering and regenerative medicine, reflect on their effect on stem cells, and highlight current translational challenges.

PRP and articular cartilage: a clinical update

The convincing background of the recent studies, investigating the different potentials of platelet-rich plasma, offers the clinician an appealing alternative for the treatment of cartilage lesions and osteoarthritis. Recent evidences in literature have shown that PRP may be helpful both as an adjuvant for surgical treatment of cartilage defects and as a therapeutic tool by intra-articular injection in patients affected by osteoarthritis. In this review, the authors introduce the trophic and anti-inflammatory properties of PRP and the different products of the available platelet concentrates. Then, in a complex scenario made of a great number of clinical variables, they resume the current literature on the PRP applications in cartilage surgery as well as the use of intra-articular PRP injections for the conservative treatment of cartilage degenerative lesions and osteoarthritis in humans, available as both case series and comparative studies. The result of this review confirms the fascinating biological role of PRP, although many aspects yet remain to be clarified and the use of PRP in a clinical setting has to be considered still exploratory.

Bioactive factors in platelet-rich plasma obtained by apheresis

INTRODUCTION

The use of platelet-rich plasma (PRP) in regenerative approaches in cartilage repair is becoming more common. Information about PRP composition and its content of putative bioactive chondrogenic growth factors (GF) that may support cartilage regeneration is scarce.

METHODS

GF composition of a pool of 6 PRP preparations was determined using Protein Antibody Membrane Arrays covering 507 GF, signaling molecules, and receptors. To verify the chondrogenic GF variability in PRP, Growth Factor Antibody Membrane Arrays covering 26 GF were applied to 6 individual PRP preparations. Selected GF involved in chondrogenic differentiation were quantified by Enzyme-Linked Immunosorbent Assay (ELISA).

RESULTS

417 out of 507 possible detectable proteins were present in the PRP pool, including 76 GF. Quantification of selected chondrogenic GF by ELISA showed an average of 0.31 ng/ml bone morphogenetic protein-2, 0.50 ng/ml connective tissue growth factor, 0.76 ng/ml fibroblast growth factor-2, and 0.59 ng/ml transforming growth factor-β3.

CONCLUSION

PRP as a therapeutic option in regenerative cartilage repair strategies is a powerful tool for the local application of chondrogenic GF to the site of injury. Chondrogenic GF are present in PRP and may support cartilage repair by inducing cell differentiation and cartilage matrix formation.