The search for a useful method for the optimal cryopreservation of adipose aspirates: part II. In vivo study

Cryopreservation of Human Adipose Tissues and Adipose-Derived Stem Cells with DMSO and/or Trehalose: A Systematic Review

Adipose tissue senescence is implicated as a major player in obesity- and ageing-related disorders. There is a growing body of research studying relevant mechanisms in age-related diseases, as well as the use of adipose-derived stem cells in regenerative medicine. The cell banking of tissue by utilising cryopreservation would allow for much greater flexibility of use. Dimethyl sulfoxide (DMSO) is the most commonly used cryopreservative agent but is toxic to cells. Trehalose is a sugar synthesised by lower organisms to withstand extreme cold and drought that has been trialled as a cryopreservative agent. To examine the efficacy of trehalose in the cryopreservation of human adipose tissue, we conducted a systematic review of studies that used trehalose for the cryopreservation of human adipose tissues and adipose-derived stem cells. Thirteen articles, including fourteen studies, were included in the final review. All seven studies that examined DMSO and trehalose showed that they could be combined effectively to cryopreserve adipocytes. Although studies that compared nonpermeable trehalose with DMSO found trehalose to be inferior, studies that devised methods to deliver nonpermeable trehalose into the cell found it comparable to DMSO. Trehalose is only comparable to DMSO when methods are devised to introduce it into the cell. There is some evidence to support using trehalose instead of using no cryopreservative agent.

Cryopreservation of lipoaspirates: in vitro measurement of the viability of adipose-derived stem cell and lipid peroxidation

As the storage time of the fat tissue passes by, lipid peroxidation and creation of by‐products may take place. The objective of this study was to evaluate the cell viability and functional changes of adipose‐derived stem cells (ADSCs) in the cryopreserved lipoaspirates at different temperatures in accordance with lipid peroxidation. Lipoaspirates acquired from liposuction were divided into four different temperature groups and stored at 4°C, −20°C, −80°C, and −196°C. After isolating ADSC from each sample, gross cell morphology and cell viability were compared with doubling time and colony‐forming unit (CFU) formation ability. Acid value, that is, thiobarbituric acid value was measured to assess lipid peroxidation. No viable ADSC was observed in −20°C and −196°C samples for past 1 week and a superior number of the live cells were detected in the 4°C group compared with the −80°C group. However, the persistence of cell division and CFU formation after 1 week was only observed in adipocytes stored at −80°C. Lipid peroxidation mainly occurred at 4°C and −20°C storage samples. If the lipoaspirates were planned to be cryopreserved, it is advised to store at −80°C. However, the number of actually functional ADSCs is very low. Furthermore, even in the cryopreserved status, continuous lipid peroxidation and by‐product creation took place, suggesting shorter preservation period as possible in the clinics.

An Update on Cryopreservation of Adipose Tissue

Currently, fat transplantation occurs immediately after harvesting procedures. Because low rates of fat graft take are well reported in the literature, many patients require multiple surgical procedures for fat graft harvest. These subsequent procedures lead to increased cost, donor-site morbidity, and patient discomfort in the long term. The ability to preserve our patients' own adipose aspirate would allow us to counteract these shortcomings and ultimately improve the clinical outcome after fat grafting. Unfortunately, there is no optimal and practical adipose tissue cryopreservation protocol for use by the plastic surgeon at the present time. Because of this dilemma, the senior author (L.L.Q.P.) has investigated this concept in an effort to create a protocol that is both technically sound and clinically achievable to allow for the long-term preservation of adipose tissue. In this article, the authors aim to outline this effort, review current clinical applications that have been reported in the literature, and detail exciting future perspectives in the use of preserved lipoaspirates for repeated fat grafting procedures or in the form of cell-based therapy engineered for reconstructive endeavors for their patients.

Effect of allogeneic mesenchymal stem cells (MSCs) on corneal wound healing in dogs

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Allogeneic MSCs are safety to be transplanted by subconjunctival route.

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Allogeneic MSCs therapy seems to be efficient in improving corneal healing in dogs.

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Allogeneic MSCs therapy applied to depth corneal ulcers promoted healing in 14 days.

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The paracrine effect of MSCs must provide a rapid corneal wound healing.

Effect of Cryopreservation on Human Adipose Tissue and Isolated Stromal Vascular Fraction Cells: In Vitro and In Vivo Analyses

BACKGROUND

Adipose tissue is a source of adipose-derived stromal/stem cells for tissue engineering and reconstruction and a tissue source for fat grafts. Although liposuction is a simple procedure for the harvest of adipose tissue, the repetition of this surgical intervention can cause adverse effects to the patient and can be a limiting factor for immediate use. Cryopreservation can avoid the morbidity associated with repetitive liposuction, allowing the use of stored tissue after the initial harvest procedure. This article focuses on the characterization of fresh and cryopreserved human adipose tissue.

METHODS

Lipoaspirates from eight donors were processed as fresh adipose tissue or cryopreserved for 4 to 6 weeks. Fresh and cryopreserved tissues were collagenase digested and the stromal vascular fraction cells were characterized immediately or cryopreserved. Characterization was based on stromal vascular fraction cell proliferation and immunophenotype. In vivo fat grafting was performed in C57BL/6 green fluorescent protein mice to analyze morphology of the tissue and its adiposity using confocal microscopy, histochemical staining (i.e., hematoxylin and eosin and Masson trichrome), and immunohistochemistry (i.e., green fluorescent protein, perilipin, and CD31).

RESULTS

Although tissue and stromal vascular fraction cell cryopreservation reduced the total cell yield, the remaining viable cells retained their adhesive and proliferative properties. The stromal vascular fraction cell immunophenotype showed a significant reduction in the hematopoietic surface markers and increased expression of stromal and adipogenic markers following cryopreservation. In vivo cryopreserved fat grafts showed morphology similar to that of freshly implanted fat grafts.

CONCLUSION

In this study, the authors demonstrated that cryopreserved adipose tissue is a potential source of stromal vascular fraction cells and a suitable source for fat grafts.

Procedure, applications, and outcomes of autologous fat grafting

OBJECTIVE

To systematically review the procedure, applications, and outcomes of autologous fat grafting, a promising technique with various clinical applications.

PATIENTS AND METHODS

Literature review of publications concerning autologous fat grafting.

RESULTS

Since its introduction, lipofilling has become increasingly popular; however, its results are variable and unpredictable. Several modifications have been made to the procedures of fat harvesting, processing, and injecting. Surgical excision and low negative-pressure aspiration with large-bore cannulas minimize adipocyte damage during fat harvesting. The "wet" method of fat harvesting involves fluid injection at the donor site and facilitates lipoaspiration while minimizing pain and ecchymosis. For fat processing, centrifugation at a low speed is preferable to high-speed centrifugation, gravity separation or filtration. Fat injection at the recipient site should be performed using small-gauge cannulas in a fanning out pattern over multiple sessions, rather than a single session. Fat grafts exhibit not only dermal filler properties but also regenerative potential owing to the presence of stem cells in fat tissue. Thus, the clinical applications of autologous fat grafting include correction of secondary contour defects after breast reconstruction, release of painful scar contractures, and treatment of burn scars and radiodermatitis. Lipofilling is also used in aesthetic surgery, such as facial and hand rejuvenation, augmentation rhinoplasty, and breast and gluteal augmentation. The complications of lipofilling are minimal and include bruising, swelling, pain, infection, necrosis, and calcification.

CONCLUSIONS

Lipofilling is a low-risk procedure that can be used to correct soft-tissue defects in the face, trunk, and extremities, with minimal discomfort for patients.

Modern trends in lipomodeling

Lipomodeling is the process of relocating autologous fat to change the shape, volume, consistency, and profile of tissues, with the aim of reconstructing, rejuvenating, and regenerating body features. There have been several important advancements in lipomodeling procedures during the last thirty years. Four clinical steps are important for the success of engraftment: fat harvesting, fat processing, fat reinjection, and preconditioning of the recipient site. With the discovery of adipose derived stem cells and dedifferentiated cells, fat cells become a major tool of regenerative medicine. This article reviews recent trends in lipomodeling trying to understand most of the issues in this field.

Human Adipose Stem Cells: From Bench to Bedside

Stem cell-based therapies for repair and regeneration of different tissues are becoming more important in the treatment of several diseases. Adult stem cells currently symbolize the most available source of cell progenitors for tissue engineering and repair and can be harvested using minimally invasive procedures. Moreover, mesenchymal stem cells (MSCs), the most widely used stem cells in stem cell-based therapies, are multipotent progenitors, with capability to differentiate into cartilage, bone, connective, muscle, and adipose tissue. So far, bone marrow has been regarded as the main source of MSCs. To date, human adult adipose tissue may be the best suitable alternative source of MSCs. Adipose stem cells (ASCs) can be largely extracted from subcutaneous human adult adipose tissue. A large number of studies show that adipose tissue contains a biologically and clinically interesting heterogeneous cell population called stromal vascular fraction (SVF). The SVF may be employed directly or cultured for selection and expansion of an adherent population, so called adipose-derived stem cells (ASCs). In recent years, literature based on data related to SVF cells and ASCs has augmented considerably: These studies have demonstrated the efficacy and safety of SVF cells and ASCs in vivo in animal models. On the basis of these observations, in several countries, various clinical trials involving SVF cells and ASCs have been permitted. This review aims at summarizing data regarding either ASCs cellular biology or ASCs-based clinical trials and at discussing the possible future clinical translation of ASCs and their potentiality in cell-based tissue engineering.

Update on cryopreservation of adipose tissue and adipose-derived stem cells

This article first discusses some fundamentals of cryobiology and challenges for cell and tissue cryopreservation. Then, the results of cryopreservation of adipose cells and tissues, including adipose-derived stem cells, in the last decade are reviewed. In addition, from the viewpoint of cryobiology, some desired future work in fat cryopreservation is proposed that would benefit the optimization, standardization, and better application of such techniques.

Microfat Grafting in Nasal Surgery

BACKGROUND

Injectable fillers are sometimes necessary to correct slight skin irregularities. However, there have been reports of necrosis after injection of alloplastic materials and heterogeneous transplants. On the other hand, the advantages of autogenous tissue grafts over those fillers are well established. Volumetric reshaping of the face with autologous tissue injection is a popular and reliable method with good long-term results. However, procedures performed on the fragile skin of the nose are prone to complications.

OBJECTIVES

The author conducted a study of injectable autologous microfat grafting to the nose in patients with secondary nasal deformities.

METHODS

During a 5-year period, 313 patients who had secondary nasal deformities with slight skin irregularities or severe nasal skin damage were treated with microfat grafting. At each patient's first injection session, excess harvested fat was cryopreserved for subsequent injection. To correct minor irregularities, 0.3 to 0.8 mL of microfat was injected during each session; for major irregularities or defects, 1 to 6 mL was required for each session.

RESULTS

One to 3 injections of microfat provided satisfactory results in all patients who had minor irregularities. For patients with multiple and severe irregularities, 3 to 6 injections were necessary and resulted in high patient satisfaction. In another group of patients, with severe traumatic skin damage, 6 to 16 injections were necessary for reconstruction. After repeated injections, each patient's skin damage was repaired.

CONCLUSIONS

Autologous microfat injection appears to be safe and effective for correcting slight irregularities of the nose.

LEVEL OF EVIDENCE

4.

Facial rejuvenation with staged injections of cryopreserved fat and tissue cocktail: clinical outcomes in the past 10 years

BACKGROUND

Facial rejuvenation by autologous fat transfer is common in aesthetic plastic surgery. The main drawback is progressive resorption, requiring repeated harvesting and microfat grafting.

OBJECTIVE

The authors present a method for cryopreservation of excess harvested fat and tissue to enable subsequent use of previously harvested excess material.

METHODS

Fat grafts were harvested using a 50-mL syringe and a 3- or 4-mm cannula. A tissue "cocktail" composed of dermis, fascia, and fat was prepared from excised scar tissue, tissue from abdominoplasty, or tissue from reduction mammaplasty. Cocktail specimens were placed in sterile tubes, immersed in a liquid nitrogen tank (-196°C), and stored at -80°C. At 3- to 6-month intervals, repeated cryopreserved fat graft injections were performed. Patients were evaluated by comparing preoperative and postoperative photographs.

RESULTS

Between 2000 and 2010, a total of 5199 cryopreserved fat or tissue injections were performed in 2439 consecutive patients (age range, 19-80 years). Nasolabial folds and lips were the most common injection sites. Clinical outcomes were satisfactory, and improved contour was achieved in most patients after repeated injections.

CONCLUSIONS

Cryopreservation of excess tissue for future injection is promising since repetitive injections are often required after resorption of microfat grafts. In our study, the survival of cryopreserved tissue cocktail or fat was comparable to that of fresh fat grafts and is therefore an effective adjuvant method for facial rejuvenation.