Platelet gels

Recent Achievements in the Development of Biomaterials Improved with Platelet Concentrates for Soft and Hard Tissue Engineering Applications

Platelet concentrates such as platelet-rich plasma, platelet-rich fibrin or concentrated growth factors are cost-effective autologous preparations containing various growth factors, including platelet-derived growth factor, transforming growth factor β, insulin-like growth factor 1 and vascular endothelial growth factor. For this reason, they are often used in regenerative medicine to treat wounds, nerve damage as well as cartilage and bone defects. Unfortunately, after administration, these preparations release growth factors very quickly, which lose their activity rapidly. As a consequence, this results in the need to repeat the therapy, which is associated with additional pain and discomfort for the patient. Recent research shows that combining platelet concentrates with biomaterials overcomes this problem because growth factors are released in a more sustainable manner. Moreover, this concept fits into the latest trends in tissue engineering, which include biomaterials, bioactive factors and cells. Therefore, this review presents the latest literature reports on the properties of biomaterials enriched with platelet concentrates for applications in skin, nerve, cartilage and bone tissue engineering.

Supernatant of activated platelet-rich plasma rejuvenated aging-induced hyposalivation in mouse

Hyposalivation is a common complaint among the elderly, but no established treatment prevents age-induced hyposalivation. Platelet derivatives such as platelet-rich plasma (PRP), platelet-rich fibrin (PRF), and plasma rich in growth factor (PRGF), are used widely in different areas of regenerative medicine to enhance the wound healing processes. This study examined whether the local injection of the supernatant of activated PRP (saPRP) into the salivary gland (SG) could help prevent aging-induced SG dysfunction and explored the mechanisms responsible for the protective effects on the SG hypofunction. The platelets were separated from the blood of male SD rats (220 ± 20 g). saPRP was manufactured by removing the fibrin clot after activating platelet with calcium ionophore 10 μM (A23187). The total protein and TGF-β1 levels were significantly higher in saPRP than in PRP. Human salivary gland epithelial cell(hSGEC) was treated with saPRP or PRP after senescence through irradiation. The significant proliferation of hSGEC was observed in saPRP treated group compared to irradiation only group and irradiation + PRP group. Cellular senescence, apoptosis, and inflammation significantly reduced in saPRP group. The SG function and structural tissue remodeling by the saPRP were investigated with naturally aged mice. The mice were divided into three groups: 3 months old (3 M), 22 months old (22 M), and 22 months old treated with saPRP (22 M + saPRP). Salivary flow rate and lag time were significantly improved in 22 M + saPRP group compared to 22 M group. The histologic examinations showed the significant proliferation of acinar cell in 22 M + saPRP group. The decrease of senescence, apoptosis, and inflammation observed by western blot in 22 M + saPRP group. The saPRP induced the proliferation of hSGECs, leading to a significant decrease in cellular senescence via decrease inflammation and apoptosis, in vitro. Moreover, the acini cells of the salivary gland were regenerated, and the salivary function increased in aged mice. These results showed that saPRP could be a treatment agent against aging-induced SG dysfunction.

Treatment Effect of Platelet Gel on Reconstructing Bone Defects and Nonunions: A Review of In Vivo Human Studies

In ideal circumstances, a fractured bone can heal properly by itself or with the aid of clinical interventions. However, around 5% to 10% of bone fractures fail to heal properly within the expected time even with the aid of clinical interventions, resulting in nonunions. Platelet gel is a blood-derived biomaterial used in regenerative medicine aiming to promote wound healing and regeneration of damaged tissues. The purpose of this paper is to review relevant articles in an attempt to explore the current consensus on the treatment effect of platelet gel on reconstructing bone defects and nonunions, hoping to provide a valuable reference for clinicians to make treatment decisions in clinical practice. Based on the present review, most of the studies applied the combination of platelet gel and bone graft to reconstruct bone defects and nonunions, and most of the results were positive, suggesting that this treatment strategy could promote successful reconstruction of bone defects and nonunions. Only two studies tried to apply platelet gel alone to reconstruct bone defects and nonunions, therefore a convincing conclusion could not be made yet regarding the treatment effect of platelet gel alone on reconstructing bone defects and nonunions. Only one study applied platelet gel combined with extracorporeal shock wave therapy to reconstruct nonunions, and the results were positive; the hypothetical mechanism of this treatment strategy is reasonable and sound, and more future clinical studies are encouraged to further justify the effectiveness of this promising treatment strategy. In conclusion, the application of platelet gel could be a promising and useful treatment method for reconstructing bone defects and nonunions, and more future clinical studies are encouraged to further investigate the effectiveness of this promising treatment method.

Platelet-rich Blood Derivatives for Tendon Regeneration

Tendon injuries constitute a significant healthcare problem with variable clinical outcomes. The complex interplay of tissue homeostasis, degeneration, repair, and regeneration makes the development of successful delivery therapeutic strategies challenging. Platelet-rich hemoderivatives, a source of supra-physiologic concentrations of human therapeutic factors, are a promising application to treat tendon injuries from the perspective of tendon tissue engineering, although the outcomes remain controversial.

Topic platelet gel application in chronic diabetic foot ulcers

In this observational study performed during 45 months we evaluated patients with chronic and recalcitrant diabetic ulcers who were treated with homologous platelet gel.

METHODS

platelet gels were obtained from homologous platelet concentrates that were aliquoted and freezed, being then activated with calcium gluconate and applied in the ulcer after cleaning and debridement. We evaluated patient's comorbidities, wound characteristics (size, tissue, inflammatory signs, pain), number and time of treatment as well as outcome (classified as complete epithelialization; partial improvement- 50% reduction in wound size or pain relief; no evolution).

RESULTS

Fifty-two patients (42 males, 10 females), with a median age of 65 years (range 43-85) were proposed for platelet gel. The following associated comorbidities were observed: hypertension (n = 41), dyslipidemia (n = 29), polyneuropathy (n = 30), peripheral arteriopathy (n = 32), retinopathy (n = 21), nephropathy (n = 15), cardiac ischemic disease (n = 14), obesity (n = 9). Thirty-eight patients presented with 3 or more associated comorbidities. The more frequent ulcer locations were sole of the foot (n = 13) and heel (n = 10). The median number of applications was 16, during 8.5 weeks. Nineteen patients (44%) achieved complete healing, 3 patients (7%) had a partial response and 21 (49%) had no progression. We did not observe a statistically significant relationship between patient age and response nor between number of comorbidities and response. We observed a more favorable evolution in patients with good compliance and good glycemic control.

CONCLUSION

Platelet gel is an effective therapeutic alternative, provided compliance and effective metabolic control are ensured.

Wound healing: time to look for intelligent, 'natural' immunological approaches?

There is now good evidence that cytokines and growth factors are key factors in tissue repair and often exert anti-infective activities. However, engineering such factors for global use, even in the most remote places, is not realistic. Instead, we propose to examine how such factors work and to evaluate the reparative tools generously provided by 'nature.' We used two approaches to address these objectives. The first approach was to reappraise the internal capacity of the factors contributing the most to healing in the body, i.e., blood platelets. The second was to revisit natural agents such as whey proteins, (honey) bee venom and propolis. The platelet approach elucidates the inflammation spectrum from physiology to pathology, whereas milk and honey derivatives accelerate diabetic wound healing. Thus, this review aims at offering a fresh view of how wound healing can be addressed by natural means.