Characterization of Microfragmented Adipose Tissue Architecture, Mesenchymal Stromal Cell Content and Release of Paracrine Mediators

Chondrogenic and Osteogenic In Vitro Differentiation Performance of Unsorted and Sorted CD34+, CD146+, and CD271+ Stem Cells Derived from Microfragmented Adipose Tissue of Patients with Knee Osteoarthritis

Background/Objectives: Treatment of knee osteoarthritis (OA) with autologous stem cells from microfragmented adipose tissue (MFAT) has shown promising but varying results. Multiple stem cell types, including CD34+, CD146+, and CD271+ stem cells, have been identified within MFAT. Patient-specific heterogeneity in stem cell populations and the content of highly potent cells may be determining factors for a successful treatment outcome. The current study aimed to identify the most promising stem cell type in MFAT to treat OA, focusing on their chondrogenic and osteogenic differentiation performance. Methods: CD34+, CD146+, and CD271+ stem cells from the MFAT of eight patients with knee OA were separated using magnetic-activated cell sorting (MACS) and analyzed as subtypes. Unsorted cells were used as a control. Chondrogenic and osteogenic in vitro differentiation were assessed through Safranin-O and H&E staining, pellet size, and qPCR for chondrogenesis, as well as Alizarin Red S staining and qPCR for osteogenesis. Results: CD34+, CD146+, and CD271+ stem cells were doubled using MACS. All subtypes were able to undergo osteogenic differentiation with Alizarin Red S staining, revealing a significant increase in calcium deposits of induced cells compared to non-induced controls. CD146+ stem cells showed higher calcium deposition compared to CD34+, CD271+, and unsorted stem cells. All cell types could form chondrogenic pellets. CD271+ stem cells produced more proteoglycans, as shown by Safranin-O staining, than CD34+ and CD146+ stem cells, but not more than the unsorted stem cells. After differentiation induction, all cell types showed an upregulation of most chondrogenic and osteogenic biomarkers. Conclusions: CD146+ stem cells showed the highest osteogenic differentiation performance for calcium deposition, while CD271+ stem cells showed the greatest chondrogenic differentiation performance for proteoglycan formation. The prevalence of these stem cell types may play a critical role in the clinical effectiveness when treating OA.

Microfragmented abdominal adipose tissue-derived stem cells from knee osteoarthritis patients aged 29-65 years demonstrate in vitro stemness and low levels of cellular senescence

Purpose

To investigate the level of cellular senescence in stem cells derived from microfragmented abdominal adipose tissue harvested from patients with knee osteoarthritis (OA).

Methods

Stem cells harvested from microfragmented abdominal adipose tissue from 20 patients with knee OA, aged 29-65 years (mean = 49.8, SD = 9.58), were analysed as a function of patient age and compared with control cells exhibiting signs of cellular senescence. Steady-state mRNA levels of a panel of genes associated with senescence were measured by qPCR. Intracellular senescence-associated proteins p16 and p21, and senescence-associated β-galactosidase activity were measured by flow cytometry. Cellular proliferation was assessed using a 5-ethynyl-2'-deoxyuridine proliferation assay. Stemness was assessed by stem cell surface markers using flow cytometry and the capacity to undergo adipogenic and osteogenic differentiation in vitro.

Results

No correlation was found between cellular senescence levels of the microfragmented adipose tissue-derived stem cells and patient age for any of the standard assays used to quantify senescence. The level of cellular senescence was generally low across all senescence-associated assays compared to the positive senescence control. Stemness was verified for all samples. An increased capacity to undergo adipogenic differentiation was shown with increasing patient age (p = 0.02). No effect of patient age was found for osteogenic differentiation.

Conclusions

Autologous microfragmented adipose tissue-derived stem cells may be used in clinical trials of knee OA of patients aged 29-65 years, at least until passage 4, as they show stemness potential and negligible senescence in vitro.

Level of Evidence

Not applicable.

Microfragmented adipose tissue in the treatment of a full-thickness supraspinatus tear: a case report

A 70-year-old female presented with an 8-month history of right anterior shoulder pain and weakness, unresolved with conservative management. Among other shoulder pathology, the patient was diagnosed with a full-thickness supraspinatus tear and elected to proceed with the microfragmented adipose tissue procedure to treat the injured tendon and nearby relevant structures. Improvements in pain and function were documented along with progressive healing of the supraspinatus on ultrasound and MRI following the procedure. This case demonstrates the efficacy of microfragmented adipose tissue as a relatively novel approach to treating non-retracted, full-thickness rotator cuff tears.

Micro-Fragmented Adipose Tissue as a Natural Scaffold for Targeted Drug Delivery in Brain Cancer

Major limitations in the effective treatment of neurological cancer include systemic cytotoxicity of chemotherapy, inaccessibility, and inoperability. The capability to successfully target a drug to the tumor site(s) without incurring serious side effects-especially in the case of aggressive tumors, such as glioblastoma and neuroblastoma-would represent a significant breakthrough in therapy. Orthotopic systems, capable of storing and releasing proteins over a prolonged period at the site of a tumor, that utilize nanoparticles, liposomes, and hydrogels have been proposed. One candidate for drug delivery is Micro-Fragmented Adipose Tissue (MFAT). Easily obtained from the patient by abdominal subcutaneous liposuction (autologous), and with a high content of Mesenchymal Stem Cells (MSCs), mechanically derived nanofat is a natural tissue graft with a structural scaffold organization. It has a well-preserved stromal vascular fraction and a prolonged capacity to secrete anti-tumorigenic concentrations of pre-absorbed chemotherapeutics within extracellular vesicles. This review discusses current evidence supporting the potential of drug-modified MFAT for the treatment of neurological cancer with respect to recent preclinical and in vitro studies. Possible limitations and future perspectives are considered.

Successful isolation of viable stem cells from cryopreserved microfragmented human adipose tissue from patients with knee osteoarthritis - a comparative study of isolation by tissue explant culture and enzymatic digestion

PURPOSE

To investigate if viable stem cells could be isolated and expanded from cryopreserved microfragmented adipose tissue (AT) harvested from patients with knee osteoarthritis.

METHODS

Microfragmented abdominal AT from knee osteoarthritis patients was cryopreserved at -80 °C in cryoprotectant-medium. The samples were thawed for stem cell isolation by tissue explant culture (TEC) and enzymatic digestion (ED), respectively. Viability, population doublings, and doubling time were assessed by trypan blue staining and flow cytometry. Cell type and senescence-associated β-galactosidase activity were analyzed by flow cytometry. Osteogenic and adipogenic differentiation was assessed quantitatively by Alizarin-Red-S and Oil-Red-O staining, respectively.

RESULTS

Microfragmented AT from 7 patients was cryopreserved for a period of 46-150 days (mean (SD) 115.9 days (44.3 days)). Viable stem cells were successfully recovered and expanded from all patients using both isolation methods with no significant difference in viable population doublings or doubling time from passage 1 to 3 (p > 0.05). Low levels of senescence-associated β-galactosidase activity was detected for both methods with no significant difference between TEC and ED (p = 0.17). Stemness was verified by stem cell surface markers and osteogenic and adipogenic differentiation performance. Adventitial stem cells (CD31^-CD34⁺CD45^-CD90⁺CD146^-), pericytes (CD31^-CD34^-CD45^-CD90⁺CD146⁺), transitional pericytes (CD31^-CD34⁺CD45^-CD90⁺CD146⁺), and CD271⁺ stem cells (CD31^-CD45^-CD90⁺CD271⁺) were identified using both methods. More pericytes were present when using TEC (25% (24%)) compared to ED (3% (2%)) at passage 4 (p = 0.04).

CONCLUSIONS

Viable stem cells can be isolated and expanded from cryopreserved microfragmented AT using both TEC and ED. TEC provides more clinically relevant pericytes than ED.

Modified nanofat grafting: Stromal vascular fraction simple and efficient mechanical isolation technique and perspectives in clinical recellularization applications

Background: Nanofat grafting (NG) is a simple and cost-effective method of lipoaspirates with inter-syringe passages, to produce stromal vascular fraction (SVF) and isolate adipose-derived stem cells (ASCs). This represents a tremendous interest in the future clinical needs of tissue engineering. In this study, we optimized the NG technique to increase the yield of ASC extractions.

Methods: We analyzed three groups of SVF obtained by 20, 30, and 40 inter-syringe passages. The control group was an SVF obtained by enzymatic digestion with Celase. We studied their cell composition by flow cytometry, observed their architecture by confocal microscopy, and observed immunomodulatory properties of the ASCs from each of the SVFs by measuring inflammatory markers of macrophages obtained by an ASC monocyte co-culture.

Results: We have established the first cell mapping of the stromal vascular fraction of adipose tissue. The results showed that SVF obtained by 20 inter-syringe passages contains more statistically significant total cells, more cells expressing the ASC phenotype, more endothelial cells, and produces more CFU-F than the SVF obtained by 30 and 40 passages and by enzymatic digestion. Confocal microscopy showed the presence of residual adipocytes in SVF obtained by inter-syringe passages but not by enzymatic digestion. The functional study indicates an orientation toward a more anti-inflammatory profile and homogenization of their immunomodulatory properties.

Conclusion: This study places mechanically dissociated SVF in the center of approaches to easily extract ASCs and a wide variety and number of other progenitor cells, immediately available in a clinical setting to provide both the amount and quality of cells required for decellularized tissues.