Viable Stem Cells Are in the Injury Effusion Fluid and Arthroscopic Byproducts From Knee Cruciate Ligament Surgery: An In Vivo Analysis

Cells Remain Viable When Collected With an In-Line-Suction Tissue Collector From Byproducts of Anterior Cruciate Ligament Reconstruction Surgery

Purpose

To investigate the viability of cells collected with an in-line-suction autologous tissue collector from the tissue byproducts of arthroscopic anterior cruciate ligament (ACL) reconstruction, to characterize cells from different tissue types, and to identify mesenchymal stem cells.

Methods

Patients aged 14 to 50 years with ACL injuries requiring arthroscopic reconstruction surgery were offered enrollment and screened for participation. In total, 12 patients were enrolled in the descriptive laboratory study. Arthroscopic byproduct tissue was collected with an in-line-suction autologous tissue collector from 4 intraoperative collection sites for each patient: ACL stump, ACL fat pad, notchplasty debris, and tunnel drilling debris. All tissue samples were digested using collagenase, and the derived cellular populations were analyzed in vitro, characterizing cellular viability, proliferative potential, qualitative multipotent differentiation capacity, and cell-surface marker presence.

Results

An equivalent mass of arthroscopic byproduct tissue was taken from each of the 4 intraoperative collection sites (1.12-1.61 g, P = .433), which all showed an average viability of at least 99.95% and high average total nucleated cells (≥1.37 × 107 cells/mL). No significant differences in collected mass (P = .433), cellular viability (P = .880), or total nucleated cells (P = .692) were observed between the 4 byproduct tissues. The byproduct tissues did exhibit significant differences in monocyte (P = .037) and red blood cell (P = .038) concentrations, specifically with greater values present in the ACL stump tissue. Cells from all byproduct tissues adhered to plastic cell culture flasks. Significant differences were found between colony-forming unit fibroblast counts of the 4 byproduct tissues when plated at 106 (P = .003) and 103 (P = .016) cells as the initial seeding density. There was a significant relationship found between both the starting concentration (χ2 = 32.7, P < .001) and the byproduct tissue type (χ2 = 30.4, P < .001) to the presence of ≥80% confluency status at 10 days. Cells obtained from all 4 byproduct tissues qualitatively showed positive tri-lineage (adipocyte, osteoblast, chondroblast) differentiation potential compared with negative controls under standardized in vitro differentiation conditions. Cells derived from all 4 byproduct tissues expressed cell-surface antigens CD105+, CD73+, CD90+, CD45-, CD14-, and CD19- (>75%), and did not express CD45 (<10%). There were no statistically significant differences in cell-surface antigens between the four byproduct tissues.

Conclusions

This descriptive laboratory study demonstrated that cells derived from arthroscopic byproduct tissues of ACL reconstruction remain viable when collected with an in-line-suction autologous tissue collector and these cells meet the ISCT criteria to qualify as mesenchymal stem cells.

Clinical Relevance

It is known that viable mesenchymal stem cells reside in byproduct tissue of anterior cruciate ligament reconstruction surgery (ACLR). Practical methods to harvest these cells at the point of care require further development. This study validates the use of an in-line-suction autologous tissue collector for the harvest of viable mesenchymal stem cells after ACLR.

Biologics, Stem Cells, Growth Factors, Platelet-Rich Plasma, Hemarthrosis, and Scaffolds May Enhance Anterior Cruciate Ligament Surgical Treatment

Biologics including mesenchymal stem cells (MSCs), growth factors, and platelet-rich plasma may enhance anterior cruciate ligament (ACL) reconstruction and even ACL primary repair. In addition, hemarthrosis after acute ACL injury represents a source of biologic factors. MSCs can differentiate into both fibroblasts and osteoblasts, potentially providing a transition between the ligament or graft and bone. MSCs also produce cytokines and growth factors necessary for cartilage, bone, ligament, and tendon regeneration. MSC sources including bone marrow, synovium, adipose tissue, ACL-remnant, patellar tendon, and umbilical cord. Also, scaffolds may represent a tool for ACL tissue engineering. A scaffold should be porous, which allows cell growth and flow of nutrients and waste, should be biocompatible, and might have mechanical properties that match the native ACL. Scaffolds have the potential to deliver bioactive molecules or stem cells. Synthetic and biologically derived scaffolds are widely available. ACL reconstruction with improved outcome, ACL repair, and ACL tissue engineering are promising goals. LEVEL OF EVIDENCE: Level V, expert opinion.

Editorial Commentary: Point-of-Care Harvest and Application of Resident Stem Are Practical and Cost-Effective

Point-of-care harvest and application of residence stem cells are practical and cost-effective. Tissue formerly considered waste contains these biologically potent cells, and use of such tissue may represent a big part of biologics going forward. The practical application of orthobiologics has slowed because of 3 hurdles: the regulatory requirements of stem cell technologies; the energy, time, and money required to develop a clinical evidence base; and the expense that they present to patients and institutions. Orthobiologic technologies that are simple and cheap and that leverage tissues that are already readily available at the point of care (i.e., the surgical procedure) solve many of these challenges. Cell sources could include knee synovium, shoulder subacromial bursa, bone marrow aspirate, and anterior cruciate ligament injury effusion fluid and stump tissue. A current concern is that collagenase processing and culture expansion are steps resulting in regulatory hurdles in the United States.

Platelet-Rich Plasma Devices Can Be Used to Isolate Stem Cells From Synovial Fluid at the Point of Care

PURPOSE

To assess whether point-of-care devices designed for collecting cellular components from blood or bone marrow could be used to isolate viable stem cells from synovial fluid.

METHODS

Male and female patients older than 18 years old with either an acute, anterior cruciate ligament (ACL) injury or knee osteoarthritis (OA) with a minimum estimated 20 mL of knee effusion volunteered. Ten patients with an ACL injury and 10 patients with OA were enrolled. Two milliliters of collected synovial effusion were analyzed and cultured for cellular content. The remaining fluid was combined with whole blood and processed using a buffy-coat based platelet-rich plasma (PRP) processing system. Specimens were analyzed for cell counts, colony-forming unit (CFU) assays, differentiation assays, and flow cytometry.

RESULTS

ACL effusion fluid contained 42.1 ± 20.7 CFU/mL and OA effusion fluid contained 65.4 ± 42.1 CFU/mL. After PRP processing, the counts in ACL-PRP were 101.6 ± 66.1 CFU/mL and 114.8 ± 73.4 CFU/mL in the OA-PRP. Cells showed tri-lineage differentiation potential when cultured under appropriate parameters. When analyzed with flow cytometry, >95% of cells produced with culturing expressed cell surface markers typically expressed by known stem cell populations, specifically CD45-, CD73+, CD29+, CD44+, CD105+, and CD90+.

CONCLUSIONS

Multipotent viable stem cells can be harvested from knee synovial fluid, associated with an ACL injury or OA, and concentrated with a buffy coat-based PRP-processing device.

CLINICAL RELEVANCE

PRP devices can be used to harvest stem cells from effusion fluids. Methods to use effusion fluid associated with an ACL injury and OA should be investigated further.

Elevation of Peripheral Blood CD34+ and Platelet Levels After Exercise With Cooling and Compression

Purpose

To analyze the cellular response and chemokine profiles following exercise using cooling and blood flow restriction on the Vasper system.

Methods

Healthy male patients between the ages of 20 and 39 years were recruited. Testing was performed on the Vasper system, a NuStep cross-trainer with concomitant 4-limb venous compression with proximal arm cuffs at 40 mm Hg and proximal leg cuffs at 65 mm Hg. A cooling vest and cooling mat (8.3°C) were used. A 7-minute warm-up followed by alternating 30- and 60-second sprints with 1.5 and 2 minutes of active recovery, respectively, between each sprint. Peripheral blood was drawn before exercise, immediately following exercise (T20), 10 minutes after the first post-exercise blood draw (T30), and then every 30 minutes (T60, T90, T120, T150, T180). A blood draw occurred at 24 hours’ postexercise. Complete blood count, monoclonal flow cytometry for CD34+, and enzyme-linked immunosorbent assay were used to analyze the samples.

Results

Sixteen healthy male patients (29.5 ± 4.5years, 1.78 ± 0.05m, 83.7 ± 11.4 kg) were enrolled. There was an immediate, temporary increase in white blood cell counts, marked by an increase in lymphocyte differential (38.3 ± 6.5 to 44.3 ± 9.0%, P = .001), decrease in neutrophil differential (47.8 ± 6.6 to 42.0 ± 9.1%, P < .001), and platelets (239.5 ± 57.2 to 268.6 ± 86.3 K⋅μL^–1, P = .01). Monocytes significantly decreased from PRE to T90 (9.8 ± 1.1 to 8.9 ± 1.1K/μL, P < .001) and T120 (8.9 ± 1.1 K/μL, P < .0001). There was a significant increase in CD34+ cells (3.9 ± 2.0 to 5.3 ± 2.8 cells⋅μL^–1, P < .001). No detectable differences in measured cytokine levels of interleukin (IL)-10, IL-6, granulocyte-macrophage colony-stimulating factor , IL-1ra, tumor necrosis factor-α, or IL-2 were observed.

Conclusions

A significant elevation of peripheral blood CD34+ and platelet levels immediately following the exercise session was observed; however, there was no effect on peripheral circulation of IL-10, IL-6, IL-1ra, tumor necrosis factor-α, or IL-2.

Clinical Relevance

Exercise can be considered as a way to manipulate point-of-care blood products like platelet-rich plasma and may increase product yield.

Percutaneous Anterior Cruciate Ligament Repair With Needle Arthroscopy and Biological Augmentation

Recent advancements in orthopaedic devices have instilled a renewed interest in repair of the anterior cruciate ligament. Biological augmentation of the repair has also recently been investigated with the hopes of improving repair outcomes and improving biological healing. The advent of needle arthroscopy allows for potentially decreased recovery times and potentially reduced complication rates compared with traditional arthroscopy. The purpose of this article is to present a percutaneous technique to repair the anterior cruciate ligament with suture tape augmentation while also augmenting with the biological byproducts from the native effusion using needle arthroscopy.

Quantification and Qualification of Stem Cells From Blood After Mobilization With Filgrastim, and Concentration Using a Platelet-Rich Plasma System

PURPOSE

To determine the cellular composition of a product created with peripheral blood harvested after systemic mobilization with filgrastim and processed with one point-of-care blood concentrating system, i.e., a platelet-rich plasma (PRP) system. The second purpose was to compare mobilized platelet-rich plasma (M-PRP) with a concentrated bone marrow aspirate (cBMA) and a PRP created from the same subjects with the same PRP system.

METHODS

Ten healthy volunteer subjects were recruited for collection and analysis of 3 tissue sources: non-treated peripheral blood, bone marrow aspirate, and filgrastim-mobilized peripheral blood, involving 4 doses of weight-based filgrastim. One point-of-care blood and bone marrow concentrating system was used to create 3 products: PRP, cBMA, and M-PRP. Automated hematologic analysis was performed on all products to quantify total red blood cells, white blood cells (WBCs), monocyte, platelet, and hematopoietic progenitor cell (HPC) concentrations. Flow cytometry was used to determine hematopoietic and mesenchymal progenitor cell populations. Lastly, concentrates were cultured and fibroblast colony-forming units (CFU-F) and morphology of adherent cells were evaluated.

RESULTS

M-PRP contained a greater concentration of WBC (mean difference = 53.2 k/μL; P < .0001), monocytes (mean difference = 8.3 k/μL; P = .002), and a trend toward a greater concentration of HPC (mean difference = 200.5 /μL; P = .060) when compared with PRP. M-PRP contained a greater concentration of monocytes (mean difference = 5.5 k/μL; P = .017) and a trend toward a greater concentration of platelets (mean difference = 348 k/μL; P = .051) and HPC (mean difference = 193.4 /μL; P = .068) when compared with cBMA. M-PRP had a similar concentration of platelets to PRP (mean difference = 110 k/μL; P = .051) and PRP had a greater concentration than cBMA (mean difference = 458 k/μL; P = .003). cBMA remained the only product capable of producing CFU-Fs (446 ± 247 /mL) as neither the M-PRP nor PRP produced CFU-Fs. M-PRP produced colonies consistent with WBC.

CONCLUSIONS

M-PRP, produced with filgrastim mobilized blood and a proprietary PRP system, contained more total WBCs, monocytes, platelets, and HPCs than cBMA and more WBCs, monocytes, and HPCs than PRP.

CLINICAL RELEVANCE

Filgrastim mobilized PRP may be an alternative to cBMA for use as a point-of-care product for orthopaedic treatments.

Arthroscopic Harvest of Adipose-Derived Mesenchymal Stem Cells From the Infrapatellar Fat Pad

BACKGROUND

The successful isolation of adipose-derived mesenchymal stem cells (ADSCs) from the arthroscopically harvested infrapatellar fat pad (IFP) would provide orthopaedic surgeons with an autologous solution for regenerative procedures.

PURPOSE

To demonstrate the quantity and viability of the mesenchymal stem cell population arthroscopically harvested from the IFP as well as the surrounding synovium.

STUDY DESIGN

Descriptive laboratory study.

METHODS

The posterior border of the IFP, including the surrounding synovial tissue, was harvested arthroscopically from patients undergoing anterior cruciate ligament reconstruction. Tissue was then collected in an AquaVage adipose canister, followed by fat fractionization using syringe emulsification and concentration with an AdiPrep device. In the laboratory, the layers of tissue were separated and then digested with 0.3% type I collagenase. The pelleted stromal vascular fraction (SVF) cells were then immediately analyzed for viability, mesenchymal cell surface markers by fluorescence-activated cell sorting, and clonogenic capacity. After culture expansion, the metabolic activity of the ADSCs was assessed by an AlamarBlue assay, and the multilineage differentiation capability was tested. The transition of surface antigens from the SVF toward expanded ADSCs at passage 2 was further evaluated.

RESULTS

SVF cells were successfully harvested with a mean yield of 4.86 ± 2.64 × 10⁵ cells/g of tissue and a mean viability of 69.03% ± 10.75%, with ages ranging from 17 to 52 years (mean, 35.14 ± 13.70 years; n = 7). The cultured ADSCs composed a mean 5.85% ± 5.89% of SVF cells with a mean yield of 0.33 ± 0.42 × 10⁵ cells/g of tissue. The nonhematopoietic cells (CD45^-) displayed the following surface antigens as a percentage of the viable population: CD44⁺ (52.21% ± 4.50%), CD73⁺CD90⁺CD105⁺ (19.20% ± 17.04%), and CD44⁺CD73⁺CD90⁺CD105⁺ (15.32% ± 15.23%). There was also a significant increase in the expression of ADSC markers CD73 (96.97% ± 1.72%; P < .01), CD10 (84.47% ± 15.46%; P < .05), and CD166 (11.63% ± 7.84%; P < .005) starting at passage 2 compared with freshly harvested SVF cells. The clonogenic efficiency of SVF cells was determined at a mean 3.21% ± 1.52% for layer 1 and 1.51% ± 0.55% for layer 2. Differentiation into cartilage, fat, and bone tissue was demonstrated by tissue-specific staining and quantitative polymerase chain reaction.

CONCLUSION

SVF cells from the IFP and adjacent synovial tissue were successfully harvested using an arthroscopic technique and produced ADSCs with surface markers that meet criteria for defined mesenchymal stem cells.

CLINICAL RELEVANCE

An autologous source of stem cells can now be harvested using a simple arthroscopic technique that will allow orthopaedic surgeons easier access to progenitor cells for regenerative procedures.

Editorial Commentary: Thinking "Inside the Box" Yields the Possibility of Harvesting Stem Cells From "Inside the Injured Knee"

Looking to the injured knee for potential stem cell harvesting has attractive benefits. Stem cells can be successfully harvested but the concentrations with the current technology are lower than bone marrow or lipoaspirate sites. The technique of utilizing the knee effusion and tissue by-products after cruciate ligament injury shows future promise.