Platelet-Rich Plasma Applications for Achilles Tendon Repair: A Bridge between Biology and Surgery

A Novel Fibrin Matrix Derived from Platelet-Rich Plasma: Protocol and Characterization

Although fibrin matrices derived from Platelet-Rich Plasma (PRP) are widely used in regenerative medicine, they have some limitations that can hinder their application. Modifying the composition of the PRP-derived fibrin matrix may improve its properties, making it suitable for certain medical uses. Three types of fibrin matrices were obtained: a PRP-derived fibrin matrix (FM), a PRP-derived fibrin matrix with a high fibrinogen content and platelets (FM-HFP) and a PRP-derived fibrin matrix with a high fibrinogen content (FM-HF). The fibrinogen levels, biomechanical properties and cell behavior were analyzed. The presence of platelets in the FM-HFP generated an inconsistent fibrin matrix that was discarded for the rest of the analysis. The fibrinogen levels in the FM-FH were higher than those in the FM (p < 0.0001), with a concentration factor of 6.86 ± 1.81. The values of clotting and swelling achieved using the FM-HF were higher (p < 0.0001), with less clot shrinkage (p < 0.0001). The FM had a significantly higher stiffness and turned out to be the most adherent composition (p = 0.027). In terms of cell viability, the FM-HF showed less cell proliferation but higher live/dead ratio values (p < 0.01). The increased fibrinogen and platelet removal in the FM-HF improved its adhesion and other biomechanical properties without affecting cell viability.

Method to obtain a plasma rich in platelet- and plasma-growth factors based on water evaporation

Platelet-Rich Plasma, also known as PRP, is an autologous biologic product used in medicine as a treatment for tissue repair. Nowadays, the majority of PRP obtention methods enrich only platelets, not considering extraplatelet biomolecules, which take part in several cell processes. In the present work, a novel PRP preparation method was developed to obtain a PRP rich in both platelet and plasma extraplatelet molecules. The method is based on the evaporation of the water of the plasma using a rotary evaporator. With this new methodology an increase in plasmatic growth factors and, as a consequence, a better dermal fibroblast cell viability was achieved, compared to a standard PRP formulation. This novel PRP product obtained with this new methodology showed promising results in vitro as an improved PRP treatment in future application.

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.

Clinical Study of Platelet-Rich Plasma (PRP) for Lower Extremity Venous Ulcers: A Meta-Analysis and Systematic Review

To systematically evaluate the clinical effects of platelet-rich plasma in the treatment of lower limb venous ulcers by applying a meta-analysis method. The Pubmed, Cochrance Library, Embase, and OVID EBM Reviews databases were searched for the search terms'platelet-rich plasma" or "Plasma, Platelet-Rich" or "Platelet Rich Plasma" and "lower extremity venous ulcers' or "Leg Ulcers' or "Ulcer, Leg", and a meta-analysis was performed on the published research literature on platelet-rich plasma for lower extremity venous ulcers from January 1900 to April 2021. The outcome indicators were: post-treatment trauma area and healing rate. Revman 5.3 statistical software was applied for meta-analysis. A total of 294 patients with lower extremity venous ulcers were included in six publications, including 148 patients in the experimental group treated with PRP versus 146 patients in the control group treated with conventional therapy. There was a statistically significant difference in the Formula of an ellipse at the end of treatment (CM²) between the experimental group and the control group, with a mean difference of -1.19 (95% CI -1.80 to -0.58, P = .0001; 6 studies, 294 participants moderate quality of evidence). The difference between the healing rate of the experimental group and the control group was statistically significant, with a risk ratio (RR) of 5.73 (95% CI 3.29 - 9.99, P < .00001; 5 studies, 248 participants moderate quality of evidence).There may be publication bias for both Formula of an ellipse at the end of treatment and healing rate. This comprehensive meta-analysis of available evidence suggests that the application of PRP for lower extremity venous ulcers accelerates the wound healing process and improves wound healing rates.

Platelet-Rich Plasma for Adhesive Capsulitis: A Systematic Review

Adhesive capsulitis (AC) is a common cause of shoulder pain seen in 3%-5% of the population. Platelet-rich plasma (PRP) is platelet-rich blood with pro-inflammatory and anti-inflammatory properties that has been proposed as a treatment option for patients with AC. The purpose of this study was to analyze outcomes of range of motion (ROM) and subjective outcomes, including the visual analog scale (VAS), disability of arm, shoulder, and hand (DASH), and shoulder pain and disability index (SPADI) scores. PubMed, Embase, and Cochrane databases were searched, and manuscripts were screened using defined preferred reporting items for systematic reviews and meta-analyses (PRISMA) criteria. Two reviewers independently screened articles for inclusion/exclusion using PICOS criteria and extracted data regarding ROM and subjective outcome scores. Nineteen total articles were included. Eleven of the 19 studies recorded ROM as a dependent variable. All articles reported improved ROM with PRP injection when compared to baseline. When recording degrees of shoulder ROM in different planes at the latest follow-up, there were a total of 67 comparative data points for PRP vs. control. Of the 67 comparisons, 62 (93%) had a larger final ROM in the PRP group. VAS scores were reported in 16 of the 19 studies, DASH scores were reported in eight of the 19 articles, and SPADI scores were reported in seven of the 19 articles. VAS, DASH, and SPADI scores were all superior in the PRP group compared to the control. Two studies reported the same final VAS score, but the PRP groups had a larger overall improvement. Of the studies that reported objective ROM outcomes, the PRP group had greater ROM at the longest follow-up compared to control in the vast majority of comparisons. For the studies that reported subjective outcomes, all patients that received PRP had a decrease in VAS pain scores and an improvement in DASH and SPADI questionnaires.

Growth factors in the treatment of Achilles tendon injury

Achilles tendon (AT) injury is one of the most common tendon injuries, especially in athletes, the elderly, and working-age people. In AT injury, the biomechanical properties of the tendon are severely affected, leading to abnormal function. In recent years, many efforts have been underway to develop effective treatments for AT injuries to enable patients to return to sports faster. For instance, several new techniques for tissue-engineered biological augmentation for tendon healing, growth factors (GFs), gene therapy, and mesenchymal stem cells were introduced. Increasing evidence has suggested that GFs can reduce inflammation, promote extracellular matrix production, and accelerate AT repair. In this review, we highlighted some recent investigations regarding the role of GFs, such as transforming GF-β(TGF-β), bone morphogenetic proteins (BMP), fibroblast GF (FGF), vascular endothelial GF (VEGF), platelet-derived GF (PDGF), and insulin-like GF (IGF), in tendon healing. In addition, we summarized the clinical trials and animal experiments on the efficacy of GFs in AT repair. We also highlighted the advantages and disadvantages of the different isoforms of TGF-β and BMPs, including GFs combined with stem cells, scaffolds, or other GFs. The strategies discussed in this review are currently in the early stages of development. It is noteworthy that although these emerging technologies may potentially develop into substantial clinical treatment options for AT injury, definitive conclusions on the use of these techniques for routine management of tendon ailments could not be drawn due to the lack of data.

Method Based on Ultrafiltration to Obtain a Plasma Rich in Platelet and Plasma Growth Factors

Platelet-Rich Plasma (PRP) is an autologous biological product which, due to its regenerative capacity, is currently used in different fields of medicine. This biological treatment has proven to be effective in numerous research studies due to its high content of growth factors released by platelets. However, the current systems used to obtain PRP do not enrich the growth factors and cytokines outside platelets. Considering this, the present work aims to develop a new technique by which all the biomolecules present in plasma are enriched. Thus, a new method based on ultrafiltration has been developed for the obtaining of the novel PRP. By this method, ultrafiltration of the plasma water is carried out using a 3KDa filtering unit. The results showed that the technique was able to concentrate extraplatelet factors, such as IGF-1 and HGF, in contrast with conventional plasmas. Thus, the cultured cells responded with increased viability to this new PRP. These results could provide a new approach to the treatment of injuries requiring regenerative medicine, potentially improving the outcomes of the conventional PRPs.

Bibliometric Analysis of the Top 50 Most Cited Studies on Achilles Tendon Pathology

Background

The development of Achilles tendon treatment modalities has been rapid, and it is increasingly difficult for clinicians to stay up to date with the most influential studies in this field. In order to fully understand the current state of the literature regarding Achilles tendon injury, it is invaluable to be familiar with the foundational articles and studies upon which the field is built.

Purpose

To objectively determine the 50 most frequently cited studies in Achilles tendon pathology and to conduct a bibliometric analysis.

Study Design

Cross-sectional study.

Methods

The Clarivate Analytics Web of Knowledge database was used to gather data and metrics of Achilles tendon research. The 50 most cited articles were selected for analysis from an initial 17,244 identified articles. The information extracted for each article included author name, publication year, country of origin, journal name, study type, and level of evidence.

Results

For these 50 studies, the total number of citations was calculated to be 13,159, with a mean of 263.2 citations per paper. The most cited article collected 657 citations. The publication dates of the 50 studies included in this analysis spanned 41 years (1972-2013). The largest number of articles were published by Swedish authors (n = 14); however, many other countries were represented, including Canada and Finland (n = 6 articles each). The most prevalent study designs were cohort studies (n = 13) with level 4 evidence studies being the most common (n = 14).

Conclusion

Among the 50 most influential articles in Achilles tendon pathology, the study designs most commonly used were cohort studies and review articles. Sweden was the country of origin for the most studies included on this list, which reflects this country's interest and commitment to researching Achilles tendon injuries and treatments.

Efficacy of Platelet-Rich Plasma in Women with a History of Embryo Transfer Failure: A Systematic Review and Meta-Analysis with Trial Sequential Analysis

Assisted reproductive technology (ART) is used to enhance pregnancy in infertile women. In this technique, the eggs are removed from the ovary and fertilized and injected with sperm to make embryos. Unfortunately, embryo implantation failures still occur in many of these women. Platelet-rich plasma (PRP) therapies use a patient's own platelets to promote tissue healing and growth, including endometrium. The growth factors provided by the platelets play a criterial role on the regenerative ability of PRP. In the last years, PRP treatments have been gaining a lot of popularity to treat women with repeated ART failures. In this study, we collected and summarized all information published in the scientific literature to assess the evidence of the PRP effect on pregnancy. We only considered randomized controlled trials (RCT), a type of study designed to be unbiased and considered at the highest level of evidence. Our analysis indicates that PRP therapies might be an effective treatment in cases of poor responsiveness to conventional ART. However, additional studies (well-designed) are necessary to confirm this beneficial effect of PRP.

Molecular and Biologic Effects of Platelet-Rich Plasma (PRP) in Ligament and Tendon Healing and Regeneration: A Systematic Review

Platelet-rich plasma (PRP) has been introduced and applied to a wide spectrum of acute and chronic ligament and tendon pathologic conditions. Although the biological effect of PRP has been studied thoroughly in both animal and human studies, there is no consensus so far on the exact mechanism of its action as well as the optimal timing and dosage of its application. Therefore, we conducted a systematic review aiming to evaluate the molecular effect of the administration of PRP in tendoligamentous injuries and degenerative diseases. The literature search revealed 36 in vitro and in vivo studies examining the healing and remodeling response of animal and human ligament or tendon tissues to PRP. Platelet-rich plasma added in the culture media was highly associated with increased cell proliferation, migration, viability and total collagen production of both ligament- and tendon-derived cells in in vitro studies, which was further confirmed by the upregulation of collagen gene expression. In vivo studies correlated the PRP with higher fibroblastic anabolic activity, including increased cellularity, collagen production and vascularity of ligament tissue. Similarly, greater metabolic response of tenocytes along with the acceleration of the healing process in the setting of a tendon tear were noticed after PRP application, particularly between the third and fourth week after treatment. However, some studies demonstrated that PRP had no or even negative effect on tendon and ligament regeneration. This controversy is mainly related to the variable processes and methodologies of preparation of PRP, necessitating standardized protocols for both investigation and ap-plication.

Interest of platelet rich plasma in Achilles tendon rupture management: a systematic review

OBJECTIVES

Acute Achilles tendon rupture (ATR) is a disabling sport-related injury. Its management involves conservative treatment with early weight-bearing or surgical treatment. Platelet-rich plasma (PRP) has raised interest as an adjuvant for treatment, given its properties on tendon repair and its anti-inflammatory effect. We aimed to assess clinical impact of PRP use in surgical or non-surgical treatment of acute ATR: range of motion, muscle strength, function, return to sport and adverse events.

METHOD

A systematic literature research was performed using PubMed, ScienceDirect, and Google Scholar databases to collect studies reporting clinical outcomes after acute ATR treated with PRP.

RESULTS

Eight studies were eligible and included 543 acute ATR. Four were randomized comparative studies. A total of 128 patients were treated surgically and 415 were treated conservatively, 271 received PRP injection. Five studies described the type of PRP used, which was variable. Only one study including 12 patients found significant outcomes in favor of the PRP group, with a 4-week earlier recovery of a normal range of motion and a 7-week earlier return to running. No difference in clinical or morphological evaluations, strength measurement, and functional outcomes was found in other studies both at short and long-term. PRP did not seem to modify the frequency of adverse events.

CONCLUSIONS

Data are not clearly in favor of a significant effect of the PRP use for treatment of ATR. There might be a slight effect on evolution during the first months. Its interest should be assessed in future studies with strong methodology.

Reconstruction of Chronic Proximal Hamstring Tear: A Novel Surgical Technique with Semitendinosus Tendon Allograft Assisted with Autologous Plasma Rich in Growth Factors (PRGF)

The reconstruction of a chronic proximal hamstring tear is a challenging pathology that posits difficulties to surgeons due to the distal retraction of the hamstring tendon stumps and the entrapment of the sciatic nerve within the scar formed around the torn hamstring tendon. We describe a novel surgical technique using a semitendinosus tendon allograft sutured in a “V inversion” manner, thereby avoiding an excess of tension and length of the new reconstructed hamstring tendons. In addition, and in order to speed up the healing process and avoid new sciatic entrapment, we assisted the surgery with liquid plasma rich in growth factors (PRGF) injected intraosseously, intratendinously and within the suture areas, as well as wrapping the sciatic nerve with a PRGF membrane. In conclusion, this novel approach offers mechanical and biological advantages to tackle the large retraction of hamstring stumps and the entrapment of the sciatic nerve within the scar.

Creating an Optimal In Vivo Environment to Enhance Outcomes Using Cell Therapy to Repair/Regenerate Injured Tissues of the Musculoskeletal System

Following most injuries to a musculoskeletal tissue which function in unique mechanical environments, an inflammatory response occurs to facilitate endogenous repair. This is a process that usually yields functionally inferior scar tissue. In the case of such injuries occurring in adults, the injury environment no longer expresses the anabolic processes that contributed to growth and maturation. An injury can also contribute to the development of a degenerative process, such as osteoarthritis. Over the past several years, researchers have attempted to use cellular therapies to enhance the repair and regeneration of injured tissues, including Platelet-rich Plasma and mesenchymal stem/medicinal signaling cells (MSC) from a variety of tissue sources, either as free MSC or incorporated into tissue engineered constructs, to facilitate regeneration of such damaged tissues. The use of free MSC can sometimes affect pain symptoms associated with conditions such as OA, but regeneration of damaged tissues has been challenging, particularly as some of these tissues have very complex structures. Therefore, implanting MSC or engineered constructs into an inflammatory environment in an adult may compromise the potential of the cells to facilitate regeneration, and neutralizing the inflammatory environment and enhancing the anabolic environment may be required for MSC-based interventions to fulfill their potential. Thus, success may depend on first eliminating negative influences (e.g., inflammation) in an environment, and secondly, implanting optimally cultured MSC or tissue engineered constructs into an anabolic environment to achieve the best outcomes. Furthermore, such interventions should be considered early rather than later on in a disease process, at a time when sufficient endogenous cells remain to serve as a template for repair and regeneration. This review discusses how the interface between inflammation and cell-based regeneration of damaged tissues may be at odds, and outlines approaches to improve outcomes. In addition, other variables that could contribute to the success of cell therapies are discussed. Thus, there may be a need to adopt a Precision Medicine approach to optimize tissue repair and regeneration following injury to these important tissues.

Healing through the lens of immunothrombosis: Biology-inspired, evolution-tailored, and human-engineered biomimetic therapies

Evolution, from invertebrates to mammals, has yielded and shaped immunoclotting as a defense and repair response against trauma and infection. This mosaic of immediate and local wound-sealing and pathogen-killing mechanisms results in survival, restoration of homeostasis, and tissue repair. In mammals, immunoclotting has been complemented with the neuroendocrine system, platelets, and contact system among other embellishments, adding layers of complexity through interconnecting blood-born proteolytic cascades, blood cells, and the neuroendocrine system. In doing so, immunothrombosis endows humans with survival advantages, but entails vulnerabilities in the current unprecedented and increasingly challenging environment. Immunothrombosis and tissue repair appear to go hand in hand with common mechanisms mediating both processes, a fact that is underlined by recent advances that are deciphering the mechanisms of the repair process and of the biochemical pathways that underpins coagulation, hemostasis and thrombosis. This review is intended to frame both the universal aspects of tissue repair and the therapeutic use of autologous fibrin matrix as a biology-as-a-drug approach in the context of the evolutionary changes in coagulation and hemostasis. In addition, we will try to shed some light on the molecular mechanisms underlying the use of the autologous fibrin matrix as a biology-inspired, evolution-tailored, and human-engineered biomimetic therapy.

An Autologous Protein-Based Topical Ointment for Hard-to-Heal Skin Wounds: A Multiple Case Series

BACKGROUND

There is increasing evidence regarding the wound healing potential of platelet-derived autologous by-products. We provide preliminary data regarding the use of a new plasma rich in growth factors-derived autologous topical ointment for the management of hard-to-heal wounds.

CASES

Four patients suffering from difficult-to-heal wounds were treated with the autologous ointment. Within 2 to 8 weeks, all wounds healed completely with no signs of infection or functional impairment of the affected limbs. No adverse events were reported.

CONCLUSION

Randomized and controlled trials are needed to determine the clinical efficacy of the autologous ointment. Nevertheless, results from this multiple case series indicate that this approach may be useful for accelerating the re-epithelization of difficult-to-heal wounds.