Engineering, differentiation and harvesting of human adipose-derived stem cell multilayer cell sheets

Cryopreserved Adipose-Derived Stem Cell Sheets: An Off-the-Shelf Scaffold for Augmenting Tendon-to-Bone Healing in a Rabbit Model of Chronic Rotator Cuff Tear

BACKGROUND

Adipose-derived stem cell (ADSC) sheets have been shown to promote tendon-to-bone healing. However, conventional laboratory preparation methods for ADSC sheets are time-consuming and risky, which precludes their diverse clinical applications.

PURPOSE

To explore the utility of off-the-shelf cryopreserved ADSC sheets (c-ADSC sheets) for rotator cuff tendon-to-bone healing.

STUDY DESIGN

Controlled laboratory study.

METHODS

The ADSC sheets were cryopreserved and thawed for live/dead double staining, TdT-mediated dUTP Nick-End Labeling (TUNEL) staining, scanning electron microscopy observation, and biomechanical testing. Clone formation, proliferative capacity, and multilineage differentiation of ADSCs within the c-ADSC sheets were assayed to explore the effect of cryopreservation on stem cell properties. A total of 67 rabbits were randomly divided into 4 groups: normal group (without supraspinatus tendon tears; n = 7), control group (repair alone; n = 20), fresh ADSC (f-ADSC) sheet group (repair; n = 20), and c-ADSC sheet group (repair; n = 20). Rabbit bilateral supraspinatus tendon tears were induced to establish a chronic rotator cuff tear model. Gross observation, micro-computed tomography analysis, histological or immunohistochemical tests, and biomechanical tests were conducted at 6 and 12 weeks after repair.

RESULTS

No significant impairment was seen in the cell viability, morphology, and mechanical properties of c-ADSC sheets when compared with f-ADSC sheets. The stem cell properties of ADSC sheets also were preserved by cryopreservation. At 6 and 12 weeks after the repair, the f-ADSC and c-ADSC sheet groups showed superior bone regeneration, higher histological scores, larger fibrocartilage areas, more mature collagen, and better biomechanical results compared with the control group. No obvious difference was seen between the f-ADSC and c-ADSC sheet groups in terms of bone regeneration, histological score, fibrocartilage formation, and biomechanical tests.

CONCLUSION

c-ADSC sheets, an off-the-shelf scaffold with a high potential for clinical translational application, can effectively promote rotator cuff tendon-to-bone healing.

CLINICAL RELEVANCE

Programmed cryopreservation of ADSC sheets is an efficient off-the-shelf scaffold for rotator cuff tendon-to-bone healing.

Translational Nanomedicines Across Human Reproductive Organs Modeling on Microfluidic Chips: State-of-the-Art and Future Prospects

Forecasting the consequence of nanoparticles (NPs) and therapeutically significant molecules before materializing for human clinical trials is a mainstay for drug delivery and screening processes. One of the noteworthy obstacles that has prevented the clinical translation of NP-based drug delivery systems and novel drugs is the lack of effective preclinical platforms. As a revolutionary technology, the organ-on-a-chip (OOC), a coalition of microfluidics and tissue engineering, has surfaced as an alternative to orthodox screening platforms. OOC technology recapitulates the structural and physiological features of human organs along with intercommunications between tissues on a chip. The current review discusses the concept of microfluidics and confers cutting-edge fabrication processes for chip designing. We also outlined the advantages of microfluidics in analyzing NPs in terms of characterization, transport, and degradation in biological systems. The review further elaborates the scope and research on translational nanomedicines in human reproductive organs (testis, placenta, uterus, and menstrual cycle) by taking the advantages offered by microfluidics and shedding light on their potential future implications. Finally, we accentuate the existing challenges for clinical translation and scale-up dynamics for microfluidics chips and emphasize its future perspectives.

Posology and Serum-/Xeno-Free Engineered Adipose Stromal Cells Cell Sheets

Well-characterized adipose stem cells and chemically defined culture media are important factors that control the production of the cell sheet, used in translational medicine. In this study, we have developed and engineered multilayer adipose stem cell cell sheets (ASCCSs) using chemically defined/serum-free culture media: undifferentiated or differentiated into osteoblasts and chondrocytes. In addition, using the cell sheet transmittance, we estimated the number of cells per cell sheet. Undifferentiated ASCCSs were engineered in 10 days, using serum-free/xeno-free culture media. They were CD29⁺, CD73⁺, CD90⁺, CD105+, HLA-A+, and HLA-DR-. ASCCSs differentiated into chondrocytes and osteoblasts were also engineered using chemically defined and animal-free culture media, in only 14 days. The addition of an ROCK inhibitor improved the chondrocyte cell sheet engineering. The decrease in the cell sheet transmittance rate was higher for the osteoblast cell sheets due to the intracellular Ca²⁺ accumulation. The estimation of cell number per cell sheet was carried out with the transmittance, which will provide important information for cell sheet posology. In conclusion, three types of ASCCSs were engineered using serum-free, xeno-free culture media, expressing their specific markers. Their transmittance measurement allowed estimating the number of cells per cell sheet, with a non-invasive methodology.

Mesenchymal stem cell-encapsulated cellulose nanofiber microbeads and enhanced biological activities by hyaluronic acid incorporation

Cell microencapsulation is a process to entrap viable and functional cells within a biocompatible and semi-permeable matrix to provide a favorable microenvironment to the cells. Cellulose nanofiber (CNF), a low-cost and sustainable cellulose-derived natural polymer, has been studied as a matrix for 3D stem cell culture in the form of a bulk hydrogel. Here, the preparation of CNF microbeads for the long-term 3D culture of human adipose-derived stem cells (hADSCs) was demonstrated. Furthermore, hyaluronic acid (HA) was physically incorporated into the stem cell encapsulated CNF microbeads with various molecular weights and concentrations to investigate its potential in enhancing the cellular bioactivities. The beneficial effects of HA incorporation on encapsulated cells were significant compared to CNF microbeads, especially with 700 kDa molecular weight and 0.2% in concentration in terms of cell proliferation (~2 times) and VEGF secretion (~2 times) while maintaining their stemness. All the results demonstrated that the HA-incorporated CNF microbeads could serve as a promising microencapsulation matrix for hADSCs.

Fate of Fat Grafting In Vivo and In Vitro: Does the Suction-Assisted Lipectomy Device Matter?

BACKGROUND

Recently, there has been increasing research interest in identifying the effect of liposuction procedures on fat graft survival in order to clarify whether different harvest techniques affect the quality of fat grafts.

OBJECTIVES

The aim of this study was to investigate the effect of 2 liposuction methods on the survival and regeneration potential of grafted fat tissue. The proliferation and differentiation potentials of adipose-derived stem cells (ASCs) isolated by both methods was also investigated.

METHODS

Fat grafts were collected from patients who underwent liposuction procedures by 2 different methods: traditional suction-assisted liposuction (TSAL) and vibration amplification of sound energy at resonance (VASER). One portion of the lipoaspirates was implanted into the subcutaneous layer of nu mice for 4 and 12 weeks. ASCs were isolated from the other portion of the lipoaspirate and subjected to proliferation and differentiation assays.

RESULTS

Although in vivo fat grafting presented similar adipose tissue survival for the 2 different liposuction methods, more angiogenesis and less fibrosis was observed in the VASER group based on histologic evaluation. Furthermore, VASER-derived ASCs presented better quality in terms of cell differentiation capacity.

CONCLUSIONS

The in vivo study confirmed better graft angiogenesis with less inflammation, apoptosis, and scar formation in the VASER group. ASCs harvested with VASER exhibited increased differentiation capacity compared with those obtained by TSAL, and represent an excellent source for fat grafting and regenerative medicine.

Measurement of the Adipose Stem Cells Cell Sheets Transmittance

In the field of cell therapy, the interest in cell sheet technology is increasing. To determine the cell sheet harvesting time requires experience and practice, and different factors could change the harvesting time (variability among donors and culture media, between cell culture dishes, initial cell seeding density). We have developed a device that can measure the transmittance of the multilayer cell sheets, using a light emitting diode and a light detector, to estimate the harvesting time. The transmittance of the adipose stromal cells cell sheets (ASCCS) was measured every other day as soon as the cells were confluent, up to 12 days. The ASCCS, from three different initial seeding densities, were harvested at 8, 10, and 12 days after seeding. Real-time PCR and immunostaining confirmed the expression of specific cell markers (CD29, CD73, CD90, CD105, HLA-A, HLA-DR), but less than the isolated adipose stromal cells. The number of cells per cell sheets, the average thickness per cell sheet, and the corresponding transmittance showed no correlation. Decrease of the transmittance seems to be correlated with the cell sheet maturation. For the first time, we are reporting the success development of a device to estimate ASCCS harvesting time based on their transmittance.

Therapeutic Properties of Mesenchymal Stem Cell on Organ Ischemia-Reperfusion Injury

The shortage of donor organs is a major global concern. Organ failure requires the transplantation of functional organs. Donor’s organs are preserved for variable periods of warm and cold ischemia time, which requires placing them into a preservation device. Ischemia and reperfusion damage the organs, due to the lack of oxygen during the ischemia step, as well as the oxidative stress during the reperfusion step. Different methodologies are developed to prevent or to diminish the level of injuries. Preservation solutions were first developed to maximize cold static preservation, which includes the addition of several chemical compounds. The next chapter of organ preservation comes with the perfusion machine, where mechanical devices provide continuous flow and oxygenation ex vivo to the organs being preserved. In the addition of inhibitors of mitogen-activated protein kinase and inhibitors of the proteasome, mesenchymal stem cells began being used 13 years ago to prevent or diminish the organ’s injuries. Mesenchymal stem cells (e.g., bone marrow stem cells, adipose derived stem cells and umbilical cord stem cells) have proven to be powerful tools in repairing damaged organs. This review will focus upon the use of some bone marrow stem cells, adipose-derived stem cells and umbilical cord stem cells on preventing or decreasing the injuries due to ischemia-reperfusion.

Scaffold-Free 3-D Cell Sheet Technique Bridges the Gap between 2-D Cell Culture and Animal Models

Various tissue engineering techniques have been created in research spanning two centuries, resulting in new opportunities for growing cells in culture and the creation of 3-D tissue-like constructs. These techniques are classified as scaffold-based and scaffold-free techniques. Cell sheet, as a scaffold-free technique, has attracted research interest in the context of drug discovery and tissue repair, because it provides more predictive data for in vivo testing. It is one of the most promising techniques and has the potential to treat degenerative tissues such as heart, kidneys, and liver. In this paper, we argue the advantages of cell sheets as a scaffold-free approach, compared to other techniques, including scaffold-based and scaffold-free techniques such as the classic systemic injection of cell suspension.