gms | German Medical Science

Deutscher Kongress für Orthopädie und Unfallchirurgie (DKOU 2015)

20.10. - 23.10.2015, Berlin

The influence of platelet concentration on mechanical and biological properties of platelet rich plasma hydrogels

Meeting Abstract

  • Jagoda Jalowiec - AO Reserach Institute, Davos Platz, Switzerland
  • Ursula Menzel - AO Reserach Institute, Davos Platz, Switzerland
  • Matteo D'Este - AO Reserach Institute, Davos Platz, Switzerland
  • Jennifer Bara - AO Reserach Institute, Davos Platz, Switzerland
  • Mauro Alini - AO Reserach Institute, Davos Platz, Switzerland
  • Sophie Verrier - AO Reserach Institute, Davos Platz, Switzerland
  • presenting/speaker Marietta Herrmann - AO Reserach Institute, Davos Platz, Switzerland

Deutscher Kongress für Orthopädie und Unfallchirurgie (DKOU 2015). Berlin, 20.-23.10.2015. Düsseldorf: German Medical Science GMS Publishing House; 2015. DocGR13-1190

doi: 10.3205/15dkou460, urn:nbn:de:0183-15dkou4602

Veröffentlicht: 5. Oktober 2015

© 2015 Jalowiec et al.
Dieser Artikel ist ein Open-Access-Artikel und steht unter den Lizenzbedingungen der Creative Commons Attribution 4.0 License (Namensnennung). Lizenz-Angaben siehe http://creativecommons.org/licenses/by/4.0/.


Gliederung

Text

Objectives: Many studies have shown promising therapeutic effects of platelet rich plasma (PRP). There are however still many unanswered questions regarding its composition, properties and effectiveness. The aim of this study was to compare different PRP preparations with respect to mechanical properties of PRP gels, the content and release profile of growth factors and the viability and behavior of encapsulated cells.

Methods: PRP was prepared from human platelet concentrates (platelet concentration 5x-50x higher than in whole blood). Aggregation of platelets was induced by the addition of thrombin and incubation at 37°C for 30 min. Mechanical properties of PRP gels were evaluated using rheological analysis. Released growth factors (CCL5, PDGF-AB, PDGF-BB, VEGF, TGF-b1) were measured using ELISA. Human bone marrow mesenchymal stem cells (MSCs) were seeded into gels at a density of 125000 cells in a volume of 315 µl PRP. MSC behavior was assessed with regards to cell viability (live/dead staining and flow cytometry), cell proliferation (DNA quantification) and differential gene expression of lineage specific genes (quantitative PCR). Kruskal-Wallis statistics were applied to compare results between experimental groups.

Results and Conclusion: Rheology showed that all tested PRP gels were effectively cross-linked. A higher concentration of platelets or a higher thrombin concentration did not affect the mechanical properties of the gels. The release of growth factors following PRP activation was concentration dependent peaking within the first 12 hours and was thereafter sustained at a moderate level over the next 5 days. MSCs could be successfully cultured in all PRP gels for 7 days with cell viability ranging between 87% and 98%. At a lower platelet concentration (5x) cell viability at day 7 (92±1.4%) was higher compared to gels with higher platelet concentration (10x PRP: 87±3.7% and 50x PRP: 87±3.9%). Of all PRP preparations, only the 5x concentration gel supported MSC proliferation as shown by an increase in DNA content with 659±85 ng/gel at day 0, 1096±50 ng/gel at day 3 and 1375±182 ng/gel after 7 days of culture. Gene expression analysis revealed upregulation of the osteogenic gene Runx2 and a higher Runx2/Sox9 ratio in 5x and 10x PRP gels compared to both 50x PRP or MSCs in monolayer.

We show that the mechanical properties of PRP gels were not affected by the platelet or thrombin concentration. However, the content and release of growth factors was dependent on the platelet concentration in PRP gels. Our data suggests that cell survival and proliferation are superior at lower platelet concentrations. Interestingly, encapsulation of MSCs in PRP gels appears to promote the differentiation of MSCs towards the osteogenic lineage, which is particularly promising for the application of PRP in bone regeneration.