Effect of Oral Losartan on Orthobiologics: Implications for Platelet-Rich Plasma and Bone Marrow Concentrate-A Rabbit Study

The Current Role of Biologics for Meniscus Injury and Treatment

PURPOSE OF REVIEW

There is little doubt that the consensus has changed to favor preservation of meniscal function where possible. Accordingly, the indications for meniscal repair strategies have been refocused on the long-term interest of knee joint health. The development and refinements in surgical technique have been complemented by biological augmentation strategies to address intrinsic challenges in healing capacity of meniscal tissue, with variable effects.

RECENT FINDINGS

A contemporary approach to meniscal healing includes adequate surgical fixation, meniscal and synovial tissue stimulation, and management of the intraarticular milieu. Overall, evidence supporting the use of autogenous or allogeneic cell sources remains limited. The use of FDA-approved medications to effect biologically favorable mechanisms during meniscal healing holds promise. Development and characterization of biologics continue to advance with translational research focused on specific growth factors, cell and tissue behaviors in meniscal healing, and joint homeostasis. Although significant strides have been made in laboratory and pre-clinical studies, translation to clinical application remains challenging. Finally, expert consensus and standardization of nomenclature related to orthobiologics for meniscal preservation will be important for the advancement of this field.

Effects of oral losartan administration on homeostasis of articular cartilage and bone in a rabbit model

Background and aims

Previous work has shown that oral losartan can enhance microfracture-mediated cartilage repair in a rabbit osteochondral defect injury model. In this study, we aimed to determine whether oral losartan would have a detrimental effect on articular cartilage and bone homeostasis in the uninjured sides.

Methods

New Zealand rabbits were divided into 4 groups including normal uninjured (Normal), contralateral uninjured side of osteochondral defect (Defect), osteochondral defect plus microfracture (Microfracture) and osteochondral defect plus microfracture and losartan oral administration (10 mg/kg/day) (Losartan). Rabbits underwent different surgeries and treatment and were sacrificed at 12 weeks. Both side of the normal group and uninjured side of treatment groups tibias were harvested for Micro-CT and histological analysis for cartilage and bone including H&E staining, Herovici's staining (bone and cartilage) Alcian blue and Safranin O staining (cartilage) as well as immunohistochemistry of losartan related signaling pathways molecules for both cartilage and bone.

Results

Our results showed losartan oral treatment at 10 mg/kg/day slightly increase Alcian blue positive matrix as well as decrease collagen type 3 in articular cartilage while having no significant effect on articular cartilage structure, cellularity, and other matrix. Losartan treatment also did not affect angiotensin receptor type 1 (AGTR1), angiotensin receptor type 2 (AGTR2) and phosphorylated transforming factor β1 activated kinase 1 (pTAK1) expression level and pattern in the articular cartilage. Furthermore, losartan treatment did not affect microarchitecture of normal cancellous bone and cortical bone of tibias compared to normal and other groups. Losartan treatment slightly increased osteocalcin positive osteoblasts on the surface of cancellous bone and did not affect bone matrix collagen type 1 content and did not change AGTR1, AGTR2 and pTAK1 signal molecule expression.

Conclusion

Oral losartan used as a microfracture augmentation therapeutic does not have significant effect on uninjured articular cartilage and bone based on our preclinical rabbit model. These results provided further evidence that the current regimen of using losartan as a microfracture augmentation therapeutic is safe with respect to bone and cartilage homeostasis and support clinical trials for its application in human cartilage repair.

VEGF-attenuated platelet-rich plasma improves therapeutic effect on cartilage repair

Autologous platelet-rich plasma (PRP) has gained popularity as a less invasive treatment for various musculoskeletal tissue injuries and conditions due to its favorable safety profile, minimal manipulation and cost-effectiveness. Although PRP treatment has been clinically used for the treatment of osteoarthritis (OA) and damaged cartilage, evidence on therapeutic efficacy has been inconsistent, which calls for a methodology to achieve consistent and improved treatment outcomes. Given that PRP contains numerous proteins, we hypothesized that attenuation of a growth factor known to be detrimental to the healing tissue would enhance efficacy of PRP treatment. Considering that VEGF-mediated angiogenesis inhibits the repair of articular cartilage, we developed VEGF-attenuated PRP by sequestering VEGF in PRP using VEGF-binding microspheres. We demonstrated that VEGF attenuation in PRP did not inhibit the effect of PRP on chondrogenic differentiation of stem cells in vitro. In addition, healing of rat OA cartilage was significantly improved after treatment with VEGF-attenuated PRP when compared to the PRP treatment group or PBS control group. We expect that attenuation of unwanted biological activity using growth factor-binding microspheres could provide a new PRP customization method broadly applicable to various tissue repair processes.

A Strategic and Worldwide Cooperative Challenge Required for the Next Generation of Platelet Concentrates

Blood-derived biomaterials, which are represented by platelet-rich plasma (PRP) or more recently by platelet-rich fibrin (PRF), have been used in regenerative therapy for almost 30 years [...].

The future of meniscus science: international expert consensus

Purpose

The purpose of this study was to evaluate the main focus areas for research and development for furthering the state of meniscus science in 2021.

Methods

An electronic survey including 10 questions was sent in a blind fashion to the faculty members of the 5^th International Conference on Meniscus Science and Surgery. These faculty served as an expert consensus on the future of research and development areas of meniscus science. Survey responses were analyzed using descriptive statistics and ranking weighted averages were calculated to score survey questions.

Results

Of the 82 faculty, 76 (93%) from 18 different countries completed the survey (84% male, 16% female). The highest ranked future research and development focus areas were meniscus repair, biologics, osteotomy procedures, addressing meniscus extrusion, and the development of new therapies for the prevention of posttraumatic osteoarthritis. Currently, the most ‘valuable’ type of biologic reported for meniscus treatment was platelet-rich plasma. The main reported global research limitation was a lack of long-term clinical outcomes data. The most promising emerging medical technologies for improving meniscus science were 3-D printing, personalized medicine, and artificial implants.

Conclusions

This survey suggests that the future of meniscus science should be focused on meniscal preservation techniques through meniscus repair, addressing meniscal extrusion, and the use of orthobiologics. The lack of long-term clinical outcomes was the main reported research limitation globally for meniscus treatment. Future product development utilizing emerging medical technologies suggest the use of 3-D printing for meniscal transplants/scaffolds, personalized treatment, and bioengineering for artificial implants.

Level of Evidence

Level V.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40634-021-00345-y.