Three dimensional scaffolds are becoming increasingly popular in the treatment of cartilage defects. Platelet-rich plasma (PRP) and fibrinogen can be used potentially as a three dimensional cell delivery vehicle. PRP is a fraction of plasma containing high levels of growth factors such as PDGF, IGF-I and TGF-I, which stimulate chondrocyte to synthesize extracellular matrix. The aim of this study was to prepare grafts based on fibrinogen, and PRP with fibrinogen as a chondrocyte carrier. Another goal was to estimate tranexamic acid as an antifibrynolytic agent in chondrocyte grafts and in monolayer culture for about 3 weeks. 450 ml blood was collected to produce fibrinogen and PRP from a Regional Blood Center voluntary donor. To prepare gel grafts, chondrocytes were mixed with PRP and, fibrinogen and then with thrombin in calcium chloride. Different doses of tranexamic acid or aprotinin were used to stabilize the constructs. Grafts were cultivated for 4 weeks in vitro to evaluate and compare their disintegration. Grafts were stable for the entire observation period and revealed no shrinkage. During graft storage, cells appeared to be viable, and cell migration from the graft to the culture plate was observed. Chondrocyte graft preparation based on PRP and fibrinogen is a promising method. PRP-fibrinogen carrier in combination with cells constitutes highly plastic and adhesive grafts. Tranexamic acid can be used as an anti-fibrinolytic agent in chondrocyte graft preparation instead of aprotinin.

Platelet-rich plasma (PRP) is commonly used in many medicinal fields and the interest in its application for management of numerous pathologies is recently growing. Platelets (PLT) contain physiologically active proteins called growth factors (GFs) that accelerate tissue regeneration. This process of tissue regeneration is stimulated through application of PRP prepared from autologous blood according to special protocol. The purpose of the protocol is to achieve high concentration of platelets within a small volume of plasma. PRP is a biological product with a platelet concentration above the baseline for the patient's peripheral blood. The PRP therapy is based on autologous procedures therefore the risk of infection is remote although some clinical conditions preclude the use of PRP as it may induce adverse reactions. The procedure of PRP preparation is relatively inexpensive and can be performed quickly in the patient's presence. In the literature of the subject there are wide variations in PRP definitions with reference to protocols of preparation, platelet concentration and activation as well as in the manner of application to injured tissue and finally in the assessment of therapy outcome. It is therefore difficult to compare and confirm the efficacy of PRP therapy used for the management of various diseases. Authors clearly emphasize the urgent need for standardizing protocols of PRP preparation and application in various disorders. Although in general PRP therapy is considered a promising method for treatment of tissue injuries, the lack of standardized preparation procedures and ways of PRP application raises numerous questions and controversies. The aim was to present review of literature related to the use of PRP and the mechanism of action of this blood derivative.

IntroductionEncephalopathy and stroke in COVID-19 patients have been repeatedly reported. Previous reports indicate that SARS-CoV-2 infection is associated with a significantly escalated risk of ischemic stroke, especially with potentially cryptogenic stroke. Encephalopathy is also present in Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy (CADASIL). Definitive diagnosis of CADASIL is based on sequencing the NOTCH3 gene. Primary pathology is the accumulation of abnormal transmembrane deposits on vascular smooth muscle cells in the brain and other organs.Material and methodsGenome of the patient was sequenced with the average depth of coverage 32,7x and mapped to the reference genome GRCh38. The whole genome sequencing (WGS) approach identified heterozygous missense variant NOTCH3 in the exon 8. Targeted Sanger sequencing was done to confirm the presence of the variant, and to examine the closest relatives. Beside the patient, all family members were unaffected, the variant appeared de novo.ResultsIdentified variant was not reported in the GnomAD v.3 and 1000 Genomes, nor in polymorphism database dbSNP. No clinical information was available in ClinVar. The only information regarding variants in the same amino acid position (Cs440Ser and Cys440Gly) from LOVD database were reported by Markus et al. They were found in 2 individuals affected with CADASIL and interpreted as pathogenic on the basis of symptoms and familial cosegregation. Beside the patient, all family members were unaffected, the variant appeared de novo.ConclusionsThe simultaneous COVID-19 infection could probably provoke an exacerbation of a previously asymptomatic CADASIL patient and could lead to an acute ischemic multi-infarct encephalopathy.