Effects of Platelet-Rich Plasma on Cellular Populations of the Central Nervous System: The Influence of Donor Age.

Platelet-rich plasma (PRP) is a biologic therapy that promotes healing responses across multiple medical fields, including the central nervous system (CNS). The efficacy of this therapy depends on several factors such as the donor's health status and age. This work aims to prove the effect of PRP on cellular models of the CNS, considering the differences between PRP from young and elderly donors. Two different PRP pools were prepared from donors 65‒85 and 20‒25 years old. The cellular and molecular composition of both PRPs were analyzed. Subsequently, the cellular response was evaluated in CNS in vitro models, studying proliferation, neurogenesis, synaptogenesis, and inflammation. While no differences in the cellular composition of PRPs were found, the molecular composition of the Young PRP showed lower levels of inflammatory molecules such as CCL-11, as well as the presence of other factors not found in Aged PRP (GDF-11). Although both PRPs had effects in terms of reducing neural progenitor cell apoptosis, stabilizing neuronal synapses, and decreasing inflammation in the microglia, the effect of the Young PRP was more pronounced. In conclusion, the molecular composition of the PRP, conditioned by the age of the donors, affects the magnitude of the biological response.

Assessment of the Behavior of Mesenchymal Stem Cells Immobilized in Biomimetic Alginate Microcapsules.

The combination of mesenchymal stem cells (MSCs) and biomimetic matrices for cell-based therapies has led to enormous advances, including the field of cell microencapsulation technology. In the present work, we have evaluated the potential of genetically modified MSCs from mice bone marrow, D1-MSCs, immobilized in alginate microcapsules with different RGD (Arg-Gly-Asp) densities. Results demonstrated that the microcapsules represent a suitable platform for D1-MSC encapsulation since cell immobilization into alginate matrices does not affect their main characteristics. The in vitro study showed a higher activity of D1-MSCs when they are immobilized in RGD-modified alginate microcapsules, obtaining the highest therapeutic factor secretion with low and intermediate densities of the bioactive molecule. In addition, the inclusion of RGD increased the differentiation potential of immobilized cells upon specific induction. However, subcutaneous implantation did not induce differentiation of D1-MSCs toward any lineage remaining at an undifferentiated state in vivo.

Intraosseous infiltrations of Platelet-Rich Plasma for severe hip osteoarthritis: A pilot study.

OBJECTIVE: Addressing the subchondral bone through intraosseous infiltrations of Platelet-Rich Plasma (PRP) may improve the effectiveness of this technique for severe hip osteoarthritis (HOA). METHODS: Forty patients with HOA degree 2 and 3 according to the Tönnis scale were recruited for this study. They were susceptible to a total hip arthroplasty, without response to previous treatment based on intraarticular infiltrations of PRP. Patients received a combination of intraosseous injections into the acetabulum and the femoral head, as well as intraarticular PRP infiltrations. The clinical outcome was evaluated at 2, 6 and 12 months using the Hip Osteoarthritis Outcome Score (HOOS) and the Western Ontario and McMaster Universities Osteoarthritis (WOMAC) Index. RESULTS: At 2, 6 and 12 months, patients had significant pain improvement according to HOOS pain, WOMAC pain, and VAS scores. After the treatment, the percentage of patients with minimal clinically important improvement was 40% (16 over 40 patients) at 2 months, 37.5% (15 over 40) at 6 months, and 40% (16 over 40) at 12 months. Conclusion: The combination of intra-articular and intra-osseous infiltrations of PRP showed a pain reduction and improvement in hip joint functionality up to 12 months in patients with severe HOA, with no severe adverse effects.

Biological and structural effects after intraosseous infiltrations of age-dependent platelet-rich plasma: An in vivo study.

Platelet-rich plasma (PRP) is an increasingly widespread treatment for joint pathologies. Its characteristics and administration route are variables that may influence the clinical outcome. The aim of this in vivo study was to analyze in aged rats the biological and structure effects of intraosseous infiltrations of two different types of PRP obtained from young and old donors. During 6 months intraosseous infiltrations were performed and 4 days after the last infiltration, animals were sacrificed, and bones were extracted for micro-computed tomography (micro-CT) and histological analysis. Molecular composition of the PRP of aged donors presented higher levels of proinflammatory molecules. The histological studies showed a greater cellularity of bone marrow in groups treated with PRP. Concerning micro-CT analysis, young PRP showed a better femoral bone structure according to values of percentage of trabecular bone, trabecular space, trabecular density, and subchondral bone plate volume. In summary, this study has demonstrated that intraosseous infiltrations of PRP from young donors prevent from age-related bone degeneration. This treatment could stimulate the biological processes that maintain homeostasis and bone structure and avoid osteoarticular pathologies.

Platelet-rich plasma combined with allograft to treat osteochondritis dissecans of the knee: a case report.

BACKGROUND: Osteochondritis dissecans of the knee is a prevalent pathology in young, active people that is brought about by either traumatic, developmental, or iatrogenic etiologies. CASE PRESENTATION: A 40-year-old Caucasian man reporting pain, swelling, and functional reduction was evaluated and diagnosed with internal condyle osteochondritis dissecans of the knee. Harnessing the trophic, chondroprotective, anti-inflammatory, and immunomodulatory properties of platelet-rich plasma, we carried out a knee open-sky surgical technique in which we combined autologous therapy with osteochondral allograft to treat the focal, large, and deep traumatic-iatrogenic osteochondritis dissecans of the knee. The axial computed tomographic scan taken 1 year after surgery revealed an area of abnormal signal intensity that was reduced on a computed tomographic scan 2 years later. The computed tomographic scan obtained 2 years later and the magnetic resonance imaging scan 3 years later also showed a clear reattachment and incorporation of the graft. Seven years after the surgery, the patient resumed his daily routine without any recurrent symptoms. CONCLUSION: Platelet-rich plasma application in osteochondral allograft implantation open surgery could enhance the healing process of medial condyle osteochondritis dissecans of the knee.

Treating Severe Knee Osteoarthritis with Combination of Intra-Osseous and Intra-Articular Infiltrations of Platelet-Rich Plasma: An Observational Study.

OBJECTIVE: Assessing the therapeutic effects of a combination of intra-articular and intra-osseous infiltrations of platelet-rich plasma (PRP) to treat severe knee osteoarthritis (KOA) using intra-articular injections of PRP as the control group. DESIGN: In this observational study, 60 patients suffering from severe KOA were treated with intra-articular infiltrations of PRP (IA group) or with a combination of intra-osseous and intra-articular infiltrations of PRP (IO group). Both groups were matched for sex, age, body mass index, and radiographic severity (III and IV degree according to Ahlbäck scale). Clinical outcome was evaluated at 2, 6, and 12 months, using the Knee injury and Osteoarthritis Outcome Score (KOOS) and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) questionnaires. RESULTS: At 2, 6 and 12 months after treatment, IO group had a significant improvement in all KOOS and WOMAC subscales ( P < 0.05). On the contrary, patients of the IA group did not improve in any of the scores. Sixteen out of 30 IO group patients showed minimal clinically important improvement (MCII) whereas 8 out of 30 IA group patients showed this response at 6 months (26.7%; 95% CI -0.4 to 49.9; P = 0.037). At 12 months, 14 patients of IO group and 5 patients of the IA group showed MCII (30%; 95% CI 4.3 to 51.9; P = 0.013). No differences between groups were observed at 2 months. CONCLUSIONS: PRP intra-articular injections in severe KOA were not effective and did not provide any benefit. Combination of intra-articular and intra-osseous infiltrations of PRP was not clinically superior at 2 months, but it showed superior clinical outcomes at 6 and 12 months when compared with intra-articular injections of PRP.

Current concepts in intraosseous Platelet-Rich Plasma injections for knee osteoarthritis.

Knee osteoarthritis (OA) is a degenerative process that slowly destroys the joints producing pain and loss of function, and diminishes the quality of life. Current treatments alleviate this symptomatology but do not stop the disease, being total knee arthroplasty the only definitive solution. Among the emerging treatments, Platelet-Rich Plasma (PRP) has shown promising results in the treatment of OA. However, to improve its effectiveness, it is necessary to approach this pathology targeting the whole joint, not only the cartilage, but including other tissues such as subchondral bone. The pathological processes that occur in the subchondral bone have influence of the cartilage loss, aggravating the disease. The combination of intraarticular infiltrations with intraosseous infiltrations regulates the biological processes of the tissues, reducing the inflammatory environment and modulating the overexpression of biomolecules that generate an aberrant cellular behavior. Although the first clinical results using this technique are promising, further research and developing adequate protocols are necessary to achieve good clinical results.

Autologous bioscaffolds based on different concentrations of platelet rich plasma and synovial fluid as a vehicle for mesenchymal stem cells.

In the field of tissue engineering, diverse types of bioscaffolds are being developed currently for osteochondral defect applications. In this work, a novel scaffold based on platelet rich plasma (PRP) and hyaluronic acid with mesenchymal stem cells (MSCs) has been evaluated to observe its effect on immobilized cells. The bioscaffolds were prepared by mixing different volumes of synovial fluid (SF) with PRP from patients obtaining three formulations at PRP-SF ratios of 3:1, 1:1 and 1:3 (v/v). The live/dead staining revealed that although the cell number of each type of bioscaffold was different, these this constructs provide cells with a suitable environment for their viability and proliferation. Moreover, immobilized MSCs showed their ability to secrete fibrinolytic enzymes, which vary depending on the fibrin amount of the scaffold. Immunohistochemical analysis revealed the positive staining for collagen type II in all cases, proving the biologic action of SF derived MSCs together with the suitable characteristics of the bioscaffold for chondrogenic differentiation. Considering all these aspects, this study demonstrates that these cells-based constructs represent an attractive method for cell immobilization, achieving completely autologous and biocompatible scaffolds. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 377-385, 2018.

Platelet-rich plasma, an adjuvant biological therapy to assist peripheral nerve repair.

Therapies such as direct tension-free microsurgical repair or transplantation of a nerve autograft, are nowadays used to treat traumatic peripheral nerve injuries (PNI), focused on the enhancement of the intrinsic regenerative potential of injured axons. However, these therapies fail to recreate the suitable cellular and molecular microenvironment of peripheral nerve repair and in some cases, the functional recovery of nerve injuries is incomplete. Thus, new biomedical engineering strategies based on tissue engineering approaches through molecular intervention and scaffolding offer promising outcomes on the field. In this sense, evidence is accumulating in both, preclinical and clinical settings, indicating that platelet-rich plasma products, and fibrin scaffold obtained from this technology, hold an important therapeutic potential as a neuroprotective, neurogenic and neuroinflammatory therapeutic modulator system, as well as enhancing the sensory and motor functional nerve muscle unit recovery.

Correction: Platelet-rich plasma, an adjuvant biological therapy to assist peripheral nerve repair.

[This corrects the article on p. 47 in vol. 12, PMID: 28250739.].

Intraosseous Infiltration of Platelet-Rich Plasma for Severe Hip Osteoarthritis.

This work describes a technique of platelet-rich plasma (PRP) infiltration for the treatment of severe hip osteoarthritis (OA). Although the results achieved with intra-articular infiltrations of PRP are promising, they may be insufficient in the long-term for severe hip OA. The technique consists of a combined intra-articular and intraosseous infiltration of PRP to reach all joint tissues, especially the subchondral bone, and hence facilitate a greater distribution of PRP. Diagnosis is based on clinical and radiographic findings, and patients with grade III OA according to the Tönnis scale, as well as patients who have not responded to conventional treatment, are considered candidates for this technique. After an ultrasound-guided intra-articular PRP infiltration is performed, 2 intraosseous infiltrations are conducted with a fluoroscope; the first injection is applied into the acetabulum and the second into the femoral head. However, this technique presents more difficulty than the conventional administration, so it is necessary to consider several aspects described in this work.

Cryopreservation of Human Mesenchymal Stem Cells in an Allogeneic Bioscaffold based on Platelet Rich Plasma and Synovial Fluid.

Transplantation of mesenchymal stem cells (MSCs) has emerged as an alternative strategy to treat knee osteoarthritis. In this context, MSCs derived from synovial fluid could provide higher chondrogenic and cartilage regeneration, presenting synovial fluid as an appropriate MSCs source. An allogeneic and biomimetic bioscaffold composed of Platelet Rich Plasma and synovial fluid that preserve and mimics the natural environment of MSCs isolated from knee has also been developed. We have optimized the cryopreservation of knee-isolated MSCs embedded within the aforementioned biomimetic scaffold, in order to create a reserve of young autologous embedded knee MSCs for future clinical applications. We have tested several cryoprotectant solutions combining dimethyl sulfoxide (DMSO), sucrose and human serum and quantifying the viability and functionality of the embedded MSCs after thawing. MSCs embedded in bioscaffolds cryopreserved with DMSO 10% or the combination of DMSO 10% and Sucrose 0,2 M displayed the best cell viabilities maintaining the multilineage differentiation potential of MSCs after thawing. In conclusion, embedded young MSCs within allogeneic biomimetic bioscaffold can be cryopreserved with the cryoprotectant solutions described in this work, allowing their future clinical use in patients with cartilage defects.

Evaluation of different RGD ligand densities in the development of cell-based drug delivery systems.

BACKGROUND: The inclusion of the tripeptide Arg-Gly-Asp (RGD) in otherwise inert biomaterials employed for cell encapsulation has been observed to be an effective strategy to provide the immobilized cells with a more suitable microenvironment. PURPOSE: The objective of this study was to determine the impact of different RGD densities on the behavior of baby hamster kidney (BHK) fibroblasts able to secrete vascular endothelial growth factor (VEGF) encapsulated in alginate microcapsules. METHODS: Alginate was modified by varying the concentration of RGD peptides in the coupling reaction. After obtaining four different types of alginate, cells were encapsulated in alginate-poly-L-lysine-alginate (APA) microcapsules. RESULTS AND DISCUSSION: The results obtained after viability, cell proliferation and VEGF secretion assays showed that the inclusion of RGD in alginate enhances the functionality of immobilized cells, obtaining the highest values with the intermediate RGD density. CONCLUSION: These results put in evidence that alginate modification influences the behavior of immobilized cells but even more that the employed density of the tripeptide is of crucial importance, obtaining in some cases even excessive activity of the encapsulated cells.

The synergistic effects of the RGD density and the microenvironment on the behavior of encapsulated cells: in vitro and in vivo direct comparative study.

The inclusion of the tripeptide RGD (Arg-Gly-Asp) in otherwise inert biomaterials employed for cell encapsulation has been observed to be an effective strategy to provide the immobilized cells with a more suitable microenvironment. However, some controversial results collected during the last years, especially in vivo, have questioned its effectiveness. Here, we have studied the behavior of C2 C12 myoblasts immobilized in alginate-poly-l-lysine-alginate microcapsules with different densities of RGD. The use of these microcapsules offer the advantage of avoiding native proteins influence permitting to establish direct comparisons between in vitro and in vivo assays. The results suggest that RGD-modified matrices provide higher dynamism, achieving therapeutically more active biosystems not only in vitro, but also in vivo. The highest functionality of the immobilized cells in vitro was obtained with the lowest RGD density. However, higher RGD densities were required in vivo to obtain the same effects observed in vitro. Altogether, these results suggest the lack of in vitro-in vivo correlation when cell behavior is evaluated within different RGD-tailored cell-loaded scaffolds.

Stem cells in alginate bioscaffolds.

The immobilization of cells into polymeric scaffolds releasing therapeutic factors, such as alginate microcapsules, has been widely employed as a drug-delivery system for numerous diseases for many years. As a result of the potential benefits stem cells offer, during recent decades, this type of cell has gained the attention of the scientific community in the field of cell microencapsulation technology and has opened many perspectives. Stem cells represent an ideal tool for cell immobilization and so does alginate as a biomaterial of choice in the elaboration of these biomimetic scaffolds, offering us the possibility of benefiting from both disciplines in a synergistic way. This review intends to give an overview of the many possibilities and the current situation of immobilized stem cells in alginate bioscaffolds, showing the diverse therapeutic applications they can already be employed in; not only drug-delivery systems, but also tissue engineering platforms.