Background: Platelet-rich plasma (PRP) and bone marrow concentrate (BMC) are orthobiologic therapies with numerous growth factors and other bioactive molecules. Before the clinical utility of PRP and BMC is optimized as a combined therapy or monotherapy, an improved understanding of the components and respective concentrations is necessary. Purpose: To prospectively measure and compare anabolic, anti-inflammatory, and proinflammatory growth factors, cytokines, and chemokines in bone marrow aspirate (BMA), BMC, whole blood, leukocyte-poor PRP (LP-PRP), and leukocyte-rich PRP (LR-PRP) from samples collected and processed concurrently on the same day from patients presenting for elective knee surgery. Study Design: Cross-sectional study; Level of evidence, 3. Methods: Patients presenting for elective knee surgery were prospectively enrolled over a 3-week period. Whole blood from peripheral venous draw and BMA from the posterior iliac crest were immediately processed via centrifugation and manual extraction methods to prepare LR-PRP, LP-PRP, and BMC samples, respectively. BMA, BMC, whole blood, LR-PRP, and LP-PRP samples were immediately assayed and analyzed to measure protein concentrations. Results: BMC had a significantly higher interleukin 1 receptor antagonist (IL-1Ra) concentration than all other preparations (all P < .0009). LR-PRP also had a significantly higher IL-1Ra concentration than LP-PRP ( P = .0006). There were no significant differences in IL-1Ra concentration based on age, sex, body mass index, or chronicity of injury in all preparations. LR-PRP had significantly higher concentrations of platelet-derived growth factor AA (PDGF-AA) and PDGF-AB/BB than all other preparations (all P < .0006). LR-PRP also had significantly higher concentrations of matrix metalloproteinase 1 (MMP-1) and soluble CD40 ligand than all other preparations (all P < .004). LP-PRP had significantly higher concentrations of MMPs, namely MMP-2, MMP-3, and MMP-12, than all other preparations (all P < .007). Conclusion: BMC is a clinically relevant source of anti-inflammatory biologic therapy that may be more effective in treating osteoarthritis and for use as an intra-articular biologic source for augmented healing in the postsurgical inflammatory and healing phases, owing to its significantly higher concentration of IL-1Ra as compared with LR-PRP and LP-PRP. Additionally, LR-PRP had a significantly higher concentration of IL-1Ra than LP-PRP. In cases where increased vascularity and healing are desired for pathological or injured tissues, including muscle and tendon, LR-PRP may be optimal given its higher overall concentrations of PDGF, TGF-β, EGF, VEGF, and soluble CD40 ligand.

Objectives: Autologous platelet-rich plasma (PRP) and bone marrow concentrate (BMC) are orthobiologic therapies with numerous growth factors and cytokines. Mesenchymal stem cells (MSCs) are also present in BMC; however, comprise a very limited component of the available monocytes. Other clinically relevant factors and cytokines, including interleukin-1 receptor antagonist (IL-1Ra), are implicated in the anti-inflammatory and regenerative processes. Prior to optimizing the clinical utility of PRP and BMC as a combined or monotherapy, an improved understanding of the components and respective concentrations is necessary. The purpose of this study was to prospectively measure and compare anabolic, catabolic, anti-inflammatory and pro-inflammatory factors, proteins and cytokines present in bone marrow aspirate (BMA), BMC, whole blood, leukocyte poor (LP)-PRP and leukocyte rich (LR)-PRP from samples collected and processed concurrently from patients presenting for elective knee surgery. Methods: A total of 31 patients presenting for elective knee surgery were prospectively enrolled over a three-week period. Whole blood from peripheral venous draw and BMA from the posterior iliac crest were immediately processed using centrifugation and manual extraction methods to create LR- and LP-PRP and BMC, respectively. BMA, BMC, whole blood, LR-PRP and LP-PRP samples were immediately assayed and analyzed to measure factor and cytokine concentrations. We strictly adhered to the minimum reporting requirements for biological outcomes (MIBO). An a priori power and sample size calculation was performed. We conservatively assumed a Bonferroni correction among all 10 pairwise comparisons, two-tailed testing, and an overall alpha level of 0.05. Eighteen subjects was sufficient to detect this magnitude of effect size with 80% statistical power. Results: BMC had a significantly higher IL-1Ra concentration than all other preparations (all p < 0.0009, Figure 1). LR-PRP had a significantly higher IL-1Ra concentration than LP-PRP (p = 0.0006). There were no significant differences in IL-1Ra concentration based on age, gender, body mass index or chronicity of injury among all preparations (Table 1). BMC had significantly higher concentrations of leukocytes and monocytes compared to the other biologic preparations including LR-PRP. LP-PRP had significantly higher concentrations of matrix metalloproteinase (MMP)-2, MMP-3 and MMP-12 than all other preparations (all p < 0.007), while BMC had a significantly lower concentration of MMP-2 than all other preparations. LR-PRP had significantly higher concentrations of MMP-1, serum soluble CD40 ligand (sCD40 L), platelet derived growth factor (PDGF)-AA and PDGF-AB/BB than all other preparations (all p < 0.004). Conclusion: BMC is a clinically relevant source of anti-inflammatory biologic therapy that may be more effective in treating osteoarthritis and for use as an intra-articular biologic for augmented healing in the post-surgical inflammatory and healing phases due to its significantly higher concentration of IL-1Ra compared to LR-PRP and LP-PRP. Additionally, LR-PRP had a significantly higher concentration of IL-1Ra than LP-PRP. In cases where increased vascularity and healing are desired for pathological or injured tissues including muscle and tendon, LR-PRP may be optimal due to its higher overall concentrations of PDGF, TGF-β, EGF, VEGF, and sCD40 L. [Figure: see text][Table: see text]

Recent efforts have focused on customizing orthobiologics, such as platelet-rich plasma (PRP) and bone marrow concentrate (BMC), to improve tissue repair. We hypothesized that oral losartan (a TGF-β1 blocker with anti-fibrotic properties) could decrease TGF-β1 levels in leukocyte-poor PRP (LP-PRP) and fibrocytes in BMC. Ten rabbits were randomized into two groups (N = 5/group): osteochondral defect + microfracture (control, group 1) and osteochondral defect + microfracture + losartan (losartan, group 2). For group 2, a dose of 10mg/kg/day of losartan was administrated orally for 12 weeks post-operatively. After 12 weeks, whole blood (WB) and bone marrow aspirate (BMA) samples were collected to process LP-PRP and BMC. TGF-β1 concentrations were measured in WB and LP-PRP with multiplex immunoassay. BMC cell populations were analyzed by flow cytometry with CD31, CD44, CD45, CD34, CD146 and CD90 antibodies. There was no significant difference in TGF-β1 levels between the losartan and control group in WB or LP-PRP. In BMC, the percentage of CD31+ cells (endothelial cells) in the losartan group was significantly higher than the control group (p = 0.008), while the percentage of CD45+ cells (hematopoietic cells-fibrocytes) in the losartan group was significantly lower than the control group (p = 0.03).