How far have biological therapies come in regenerative sports medicine?

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.

Small interfering RNAs in the management of human osteoporosis

BACKGROUND

Osteoporosis results in reduced bone mass and consequent bone fragility. Small interfering RNAs (siRNAs) can be used for therapeutic purposes, as molecular targets or as useful markers to test new therapies.

SOURCES OF DATA

A systematic search of different databases to May 2023 was performed to define the role of siRNAs in osteoporosis therapy. Fourteen suitable studies were identified.

AREAS OF AGREEMENT

SiRNAs may be useful in studying metabolic processes in osteoporosis and identify possible therapeutic targets for novel drug therapies.

AREAS OF CONTROVERSY

The metabolic processes of osteoporosis are regulated by many genes and cytokines that can be targeted by siRNAs. However, it is not easy to predict whether the in vitro responses of the studied siRNAs and drugs are applicable in vivo.

GROWING POINTS

Metabolic processes can be affected by the effect of gene dysregulation mediated by siRNAs on various growth factors.

AREAS TIMELY FOR DEVELOPING RESEARCH

Despite the predictability of pharmacological response of siRNA in vitro, similar responses cannot be expected in vivo.

Small interfering RNAs in the management of human rheumatoid arthritis

BACKGROUND

Rheumatoid arthritis (RA) has unclear pathogenesis, but the molecules that feed its inflammatory state are known. Small interfering RNAs (siRNAs) are useful to identify molecular targets and evaluate the efficacy of specific drugs, and can themselves be used for therapeutic purposes.

SOURCES OF DATA

A systematic search of different databases to March 2022 was performed to define the role of siRNAs in RA therapy. Twenty suitable studies were identified.

AREAS OF AGREEMENT

Small interfering RNAs can be useful in the study of inflammatory processes in RA, and identify possible therapeutic targets and drug therapies.

AREAS OF CONTROVERSY

Many genes and cytokines participate in the inflammatory process of RA and can be regulated with siRNA. However, it is difficult to determine whether the responses to siRNAs and other drugs studied in human cells in vitro are similar to the responses in vivo.

GROWING POINTS

Inflammatory processes can be affected by the gene dysregulation of siRNAs on inflammatory cytokines.

AREAS TIMELY FOR DEVELOPING RESEARCH

To date, it is not possible to determine whether the pharmacological response of siRNAs on cells in vitro would be similar to what takes place in vivo for the diseases studied so far.

Small interfering RNAs in tendon homeostasis

BACKGROUND

Tenogenesis and tendon homeostasis are guided by genes encoding for the structural molecules of tendon fibres. Small interfering RNAs (siRNAs), acting on gene regulation, can therefore participate in the process of tendon healing.

SOURCES OF DATA

A systematic search of different databases to October 2020 identified 17 suitable studies.

AREAS OF AGREEMENT

SiRNAs can be useful to study reparative processes of tendons and identify possible therapeutic targets in tendon healing.

AREAS OF CONTROVERSY

Many genes and growth factors involved in the processes of tendinopathy and tendon healing can be regulated by siRNAs. It is however unclear which gene silencing determines the expected effect.

GROWING POINTS

Gene dysregulation of growth factors and tendon structural proteins can be influenced by siRNA.

AREAS TIMELY FOR DEVELOPING RESEARCH

It is not clear whether there is a direct action of the siRNAs that can be used to facilitate the repair processes of tendons.

The effect of the platelet-rich plasma and ozone therapy on tendon-to-bone healing in the rabbit rotator cuff repair model

Background

The aim of this study is to histologically and biomechanically investigate the effects of local PRP and ozone therapy (O₂O₃) on tendon-to-bone healing in a rabbit model of the supraspinatus tendon tear.

Methods

Four groups were formed to have seven rabbits in each group: repair, R; repair + PRP, RP; repair + ozone, RO; and repair + PRP + ozone, RPO. The supraspinatus tendon was detached by sharp dissection from the footprint and an acute tear pattern was created. Thereafter, tendon repair was performed with the transosseous technique. In the RP group, PRP, and in the RPO group, PRP + O2O3 mixture was injected to the tendon repair site. In the RO group, O₂O₃ gas mixture was injected into subacromial space three times a week for a total of 4 weeks. The study was ended at postoperative 6th week.

Results

When compared with the R group, a statistically significant increase was observed in the biomechanical strength of the RP and RPO groups. The highest increase in biomechanical strength was detected in the RPO group. The histology of the RO and RPO groups showed better collagen fiber continuity and orientation than the R and RP groups.

Conclusions

The results obtained from this study show that the ozonized PRP can be used as biological support to increase tendon-to-bone healing. However, these results need to be supported by clinical studies.

Mesenchymal stromal cell products for intra-articular knee injections for conservative management of osteoarthritis

Sports injuries and secondary joint problems, mainly of the knee, are common, especially in sports associated with high impact activities and/or torsional loading. The consequences can be career ending in elite athletes and reduce exercise activities in recreational people. Various cell products can be injected intra-articularly. First, fresh cellular mixtures can be prepared and injected in the same day, such as stromal vascular fraction of adipose tissue (SVF) and bone marrow concentrates (BMCs). Second, autologous mesenchymal stromal cells (MSCs) can be isolated from BMCs or SVF and, after several weeks of laboratory expansion, several millions of MSCs can be obtained for intra-articular injection. Finally, allogeneic MSCs from the bone marrow, adipose tissue or perinatal tissues of selected donors constitute an ‘off-the-shelf’ experimental treatment for injection delivery in patients with osteoarthritis of the knee. The perceived efficacy of all these products is based on the hypothesis of a paracrine mechanism of action: when living cells are delivered within the joint, they establish a molecular cross-talk with immune cells and local cell phenotypes, thereby modulating inflammation with subsequent modifications in the catabolic/degenerative milieu. Current clinical research examines whether injection delivery of MSCs translates into actual clinical benefits. Overall, clinical studies lack the quality needed to answer major research questions, including clinical and structural efficacy, optimal cell dose, and number of injections and specific protocol for cell delivery. Poor experimental designs are exacerbated by the diversity of patient phenotypes that hinder comparisons between treatments. Further understanding of disease pathology is paramount to develop potent function assays and understand whether the host tissue, the cell product or both should be primed before MSCs are injected intra-articularly.

Intra-articular platelet-rich plasma vs corticosteroids in the treatment of moderate knee osteoarthritis: a single-center prospective randomized controlled study with a 1-year follow up

BACKGROUND

Osteoarthritis is the most prevalent type of arthritis, which significantly impacts the patient's mobility and quality of life. Pharmacological treatments for osteoarthritis, such as corticosteroids, produce an immediate reduction of the patient's pain as well as an improvement in the patient's mobility and quality of life, but with a limited long-term efficacy. In this context, platelet-rich plasma (PRP) infiltrations represent a therapeutic tool due to its trophic properties and its ability to control inflammatory processes, especially in musculoskeletal applications. The aim of this study is to evaluate and compare the clinical benefits of PRP when injected intra-articularly vs a commonly used corticosteroid (CS, triamcinolone acetonide, Kenalog®) in patients affected by mild to moderate symptomatic knee osteoarthritis.

METHODS

Forty patients affected by symptomatic radiologically confirmed knee osteoarthritis (Kellgren-Lawrence grades II-III) were enrolled in this randomized study. Patients randomized in the PRP group (n = 20) received an intra-articular injection of PRP (8 mL) while patients randomized in the CS group (n = 20) received an intra-articular injection of triamcinolone acetonide (1 mL of 40 mg/mL) plus lidocaine (5 mL of 2%). The pain and function of the target knee were evaluated by the VAS, IKDC, and KSS scales at the baseline (V1), 1 week (V2), 5 weeks (V3), 15 weeks (V4), 30 weeks (V5), and 1 year (V6) after treatment.

RESULTS

No serious adverse effects were observed during the follow-up period. A mild synovitis was registered in 15 patients (75%) in the PRP group within the first week after treatment which resolved spontaneously. Both treatments were effective in relieving pain and improving the knee function in the very short-term follow-up visit (1 week). A high improvement of the subjective scores was observed for both groups up to 5 weeks, with no significative differences between the groups for the VAS, IKDC, or KSS. After 15 weeks of follow-up, the PRP group showed significative improvements in all scores when compared to the CS group. Overall, the patients who received PRP treatment had better outcomes in a longer follow-up visit (up to 1 year) than those who received CS.

CONCLUSIONS

A single PRP or CS intra-articular injection is safe and improves the short-term scores of pain and the knee function in patients affected by mild to moderate symptomatic knee OA (with no significant differences between the groups). PRP demonstrated a statistically significant improvement over CS in a 1-year follow-up. This study was registered at ISRCTN with the ID ISRCTN46024618.

Hyaluronic Acid (HA), Platelet-Rich Plasm and Extracorporeal Shock Wave Therapy (ESWT) promote human chondrocyte regeneration in vitro and ESWT-mediated increase of CD44 expression enhances their susceptibility to HA treatment

Novel strategies have been proposed for articular cartilage damage occurring during osteoarthritis (OA) and -among these- Extracorporeal Shock Wave Therapy (ESWT), intra-articular injections of Platelet-Rich Plasma (PRP) or Hyaluronic Acid (HA) revealed encouraging results. To investigate the possible mechanisms responsible for those clinical benefits, we established primary cultures of human chondrocytes derived from cartilage explants and measured the in vitro effects of ESW, PRP and HA therapies. After molecular/morphological cell characterization, we assessed those effects on the functional activities of the chondrocyte cell cultures, at the protein and molecular levels. ESWT significantly prevented the progressive dedifferentiation that spontaneously occurs during prolonged chondrocyte culture. We then attested the efficiency of all such treatments to stimulate the expression of markers of chondrogenic potential such as SOX9 and COL2A, to increase the Ki67 proliferation index as well as to antagonize the traditional marker of chondrosenescence p16INK4a (known as Cdkn2a). Furthermore, all our samples showed an ESW- and HA-mediated enhancement of migratory and anti-inflammatory activity onto the cytokine-rich environment characterizing OA. Taken together, those results suggest a regenerative effect of such therapies on primary human chondrocytes in vitro. Moreover, we also show for the first time that ESW treatment induces the surface expression of major hyaluronan cell receptor CD44 allowing the increase of COL2A/COL1A ratio upon HA administration. Therefore, this work suggests that ESW-induced CD44 overexpression enhances the in vitro cell susceptibility of human chondrocytes to HA, presumably favouring the repair of degenerated cartilage.

Drug-loaded hyaluronic acid hydrogel as a sustained-release regimen with dual effects in early intervention of tendinopathy

Resulting from accumulative microtrauma, impaired healing and oxidative stress, tendinopathy is a debilitating and relentlessly deteriorating disease that greatly affects daily function and quality of life. Current therapy usually provides symptomatic relief only. Sufferers undergo repetitive and protracted treatment courses that rarely alter the disease process. We aim to develop a sustained-release regimen with an intrinsic therapeutic effect in tendinopathy treatment, using oxidised hyaluronic acid/adipic acid dihydrazide hydrogel (HA hydrogel) as both the drug carrier and a mitigating agent of symptoms. We show that HA hydrogel can mitigate tendinopathy changes both in vitro (mechanically induced tendinopathy model) and in vivo (collagenase-induced tendinopathy model). A potent anti-oxidative (pigallocatechin gallate) incorporated into HA hydrogel conferred an additional protective effect in both models. The results indicate that when administered early, combined medications targeting different pathogenesis pathways can resolve tendinopathy. Although facilitating the healing process and mitigating oxidative stress are promising therapeutic strategies, the most effective regimen for tendinopathy treatment has to be determined yet. The established experimental model and drug carrier system provide a platform for exploring new therapeutics against this debilitating disease.

Effect of a Collagen-Based Compound on Morpho-Functional Properties of Cultured Human Tenocytes

Background: Greater Trochanter Pain Syndrome (GTPS) is the main reason for recalcitrant lateral hip pain. Gluteus medius and minimus tendinopathy plays a key role in this setting. An injectable medical compound containing collagen type I (MD-Tissue, Guna) has been produced with the aim to counteract the physiological and pathological degeneration of tendons. In this study we aimed at characterizing the effect of this medical compound on cultured human gluteal tenocytes, focusing on the collagen turnover pathways, in order to understand how this medical compound could influence tendon biology and healing. Methods: Tenocytes were obtained from gluteal tendon fragments collected in eight patients without any gluteal tendon pathology undergoing total hip replacement through an anterior approach. Cell proliferation and migration were investigated by growth curves and wound healing assay, respectively. The expression of genes and proteins involved in collagen turnover were analysed by real-time PCR, Slot blot and SDS-zymography. Results: Our data show that tenocytes cultured on MD-Tissue, compared to controls, have increased proliferation rate and migration potential. MD-Tissue induced collagen type I (COL-I) secretion and mRNA levels of tissue inhibitor of matrix metalloproteinases (MMP)-1 (TIMP-1). Meanwhile, lysyl hydroxylase 2b and matrix metalloproteinases (MMP)-1 and -2, involved, respectively, in collagen maturation and degradation, were not affected. Conclusions: Considered as a whole, our results suggest that MD-Tissue could induce in tenocytes an anabolic phenotype by stimulating tenocyte proliferation and migration and COL-I synthesis, maturation, and secretion, thus favouring tendon repair. In particular, based on its effect on gluteal tenocytes, MD-Tissue could be effective in the discouraging treatment of GTPS. From now a rigorous clinical investigation is desirable to understand the real clinical potentials of this compound.