Biomechanical study of the effect of platelet rich plasma on the treatment of medial collateral ligament lesion in rabbits

Mesenchymal Stem Cells for Enhanced Healing of the Medial Collateral Ligament of the Knee Joint

Background and Objectives: The medial collateral ligament (MCL) is one of the major supporting ligaments of the knee joint, and MCL injuries are common where excessive valgus loading is applied to the knee joint. Although most MCL injuries can be treated conservatively, healing of the MCL can take several weeks to months. Furthermore, once injured, the biomechanical properties of the healed MCL differ from those of the native MCL, resulting in an increased risk of re-injury and chronic remnant symptoms. Mesenchymal stem cells (MSCs), owing to their therapeutic potential, have been investigated in various musculoskeletal injuries, and some preclinical studies regarding MSC-based approaches in MCL injuries have shown promising results. Despite satisfactory results in preclinical studies, there is still a lack of clinical studies in the orthopedic literature. This article describes the basic knowledge of the MCL, standard treatments for MCL injuries, and recent studies regarding the application of MSCs for enhanced healing of the MCL. MSC-based approaches are expected to be a potential therapeutic option for enhanced healing of the MCL in the future.

The Efficacy of Platelet-Rich Plasma for Ligament Injuries: A Systematic Review of Basic Science Literature With Protocol Quality Assessment

Background:

Despite the existence of many clinical studies on platelet-rich plasma (PRP) interventions for ligamentous pathology, basic science consensus regarding the indications, mechanisms, and optimal composition of PRP for treating ligament injuries is lacking.

Purpose:

To (1) compare the efficacy of PRP in animal models of ligament injury with placebo and (2) describe the potential variability in PRP preparation using accepted classification systems.

Study Design:

Systematic review.

Methods:

The Cochrane Database of Systematic Reviews, Cochrane Central Register of Controlled Trials, PubMed, Embase, and Ovid MEDLINE were queried in April 2020 for in vivo and in vitro basic science studies regarding PRP use for ligament injury. Study design, results, PRP composition, and analyzed cellular and molecular markers were extracted, and outcomes relative to control models were documented. Bias was assessed using the SYRCLE risk-of-bias tool.

Results:

Included were 43 articles (31 in vivo and 12 in vitro studies) investigating the anterior cruciate ligament/cranial cruciate ligament (n = 32), medial collateral ligament (n = 6), suspensory ligament (n = 3), patellar ligament (n = 1), and Hock ligament (n = 1). Platelet concentration was reported in 34 studies (77.3%); leukocyte composition, in 12 (27.3%); and red blood cell counts, in 7 (15.9%). With PRP treatment, 5 of 12 in vitro studies demonstrated significant increases in cell viability, 6 of 12 in gene expression, 14 of 32 in vivo studies reported superior ligament repair via histological evaluation, and 13 in vivo studies reported superior mechanical properties. Variability in PRP preparation methods was observed across all articles, and only 1 study reported all necessary information to be classified by the 4 schemes we used to evaluate reporting. Among the in vivo studies, detection and performance bias were consistently high, whereas selection, attrition, reporting, and other biases were consistently low.

Conclusion:

Conflicting data on the cellular and molecular effects of PRP for ligament injuries were observed secondary to the finding that included studies were heterogeneous, limiting interpretation across studies and the ability to draw meaningful conclusions. Clinical trials and any causal relationship between PRP use in ligament injuries and its potential for regeneration and healing should be pursued with caution if based solely on basic science data.

Regeneration of grade 3 ankle sprain, using the recombinant human amelogenin protein (rHAM+ ) in a rat model

Lateral ligament tears, also known as high-grade ankle sprains, are common, debilitating, and usually heal slowly. Ten to thirty percent of patients continue to suffer from chronic pain and ankle instability even after 3 to 9 months. Previously, we showed that the recombinant human amelogenin (rHAM⁺ ) induced regeneration of fully transected rat medial collateral ligament, a common proof-of-concept model. Our aim was to evaluate whether rHAM⁺ can regenerate torn ankle calcaneofibular ligament (CFL), an important component of the lateral ankle stabilizers. Right CFLs of Sabra rats were transected and treated with 0, 0.5, or 1 µg/µL rHAM⁺ dissolved in propylene glycol alginate (PGA). Results were compared with the normal group, without surgery. Healing was evaluated 12 weeks after treatment by mechanical testing (ratio between the right and left, untransected ligaments of the same rat), and histology including immunohistochemical staining of collagen I and S100. The mechanical properties, structure, and composition of transected ligaments treated with 0.5 μg/μL rHAM⁺ (experimental) were similar to untransected ligaments. PGA (control) treated ligaments were much weaker, lax, and unorganized compared with untransected ligaments. Treatment with 1 μg/μL rHAM⁺ was not as efficient as 0.5 μg/μL rHAM⁺ . Normal arrangement of collagen I fibers and of proprioceptive nerve endings, parallel to the direction of the force, was detected in ligaments treated with 0.5 μg/μL rHAM⁺ , and scattered arrangement, resembling scar tissue, in control ligaments. In conclusion, we showed that rHAM⁺ induced significant mechanical and structural regeneration of torn rat CFLs, which might be translated into treatment for grades 2 and 3 ankle sprain injuries.

Effects of homologous and heterologous rich platelets plasma, compared to poor platelets plasma, on cutaneous healing of rabbits

Purpose:

To evaluate and compare the effects of homologous and heterologous PRP (Platelet-Rich Plasma) on the quality and speed of skin wound healing, compared to Poor Platelet Plasma (PPP).

Methods:

Twenty-one male adult rabbits were used; two for preparing homologous PRP, with the rest of them separated randomly in three groups, according to the treatment received: PPP - control (n=5), homologous PRP (n=7), heterologous (n=7). Excisional skin wounds were made on the back of the animals, for the application of homologous and heterologous PPP and PRP. At the 14th post-operative day (POD), the animals were subjected to a new wound, and the treatments were inverted. The wounds were evaluated macroscopically and histologically.

Results:

A larger percentage of scar retraction was observed on the group treated with heterologous PRP, compared to homologous PRP, at the third POD, an increase of 25.03% (p=0.01). No other statistically significant differences among treatments were observed. Among every group, skin healing was efficient, without local adverse effects.

Conclusions:

Heterologous PRP contributed with more tissue retraction at the beginning of the wound healing process. After this, there were no differences on the wound healing skin process treated with PRP or PPP. However, our findings suggest the presence of others plasmatic factors, besides platelets, which could also contribute to the wound healing process, and thus, should be further investigated.