Jingwei Feng

Therapeutic Potential of Adipose-Derived SSEA-3-Positive Muse Cells for Treating Diabetic Skin Ulcers

Stage‐specific embryonic antigen‐3 (SSEA‐3)‐positive multipotent mesenchymal cells (multilineage differentiating stress‐enduring [Muse] cells) were isolated from cultured human adipose tissue‐derived stem/stromal cells (hASCs) and characterized, and their therapeutic potential for treating diabetic skin ulcers was evaluated. Cultured hASCs were separated using magnetic‐activated cell sorting into positive and negative fractions, a SSEA‐3+ cell‐enriched fraction (Muse‐rich) and the remaining fraction (Muse‐poor). Muse‐rich hASCs showed upregulated and downregulated pluripotency and cell proliferation genes, respectively, compared with Muse‐poor hASCs. These cells also released higher amounts of certain growth factors, particularly under hypoxic conditions, compared with Muse‐poor cells. Skin ulcers were generated in severe combined immunodeficiency (SCID) mice with type 1 diabetes, which showed delayed wound healing compared with nondiabetic SCID mice. Treatment with Muse‐rich cells significantly accelerated wound healing compared with treatment with Muse‐poor cells. Transplanted cells were integrated into the regenerated dermis as vascular endothelial cells and other cells. However, they were not detected in the surrounding intact regions. Thus, the selected population of ASCs has greater therapeutic effects to accelerate impaired wound healing associated with type 1 diabetes. These cells can be achieved in large amounts with minimal morbidity and could be a practical tool for a variety of stem cell‐depleted or ischemic conditions of various organs and tissues.

Therapeutic Potential of Human Adipose-Derived Stem/Stromal Cell Microspheroids Prepared by Three-Dimensional Culture in Non-Cross-Linked Hyaluronic Acid Gel

Three‐dimensional culture of mesenchymal stem/stromal cells for spheroid formation is known to enhance their therapeutic potential for regenerative medicine. Spheroids were prepared by culturing human adipose‐derived stem/stromal cells (hASCs) in a non‐cross‐linked hyaluronic acid (HA) gel and compared with dissociated hASCs and hASC spheroids prepared using a nonadherent dish. Preliminary experiments indicated that a 4% HA gel was the most appropriate for forming hASC spheroids with a relatively consistent size (20–50 µm) within 48 hours. Prepared spheroids were positive for pluripotency markers (NANOG, OCT3/4, and SOX‐2), and 40% of the cells were SSEA‐3‐positive, a marker of the multilineage differentiating stress enduring or Muse cell. In contrast with dissociated ASCs, increased secretion of cytokines such as hepatocyte growth factor was detected in ASC spheroids cultured under hypoxia. On microarray ASC spheroids showed upregulation of some pluripotency markers and downregulation of genes related to the mitotic cell cycle. After ischemia‐reperfusion injury to the fat pad in SCID mice, local injection of hASC spheroids promoted tissue repair and reduced the final atrophy (1.6%) compared with that of dissociated hASCs (14.3%) or phosphate‐buffered saline (20.3%). Part of the administered hASCs differentiated into vascular endothelial cells. ASC spheroids prepared in a HA gel contain undifferentiated cells with therapeutic potential to promote angiogenesis and tissue regeneration after damage.

Differential contributions of graft-derived and host-derived cells in tissue regeneration/remodeling after fat grafting.

Background: Recent research indicates that the adipose tissue of nonvascularized grafts is completely remodeled within 3 months, although origins of next-generation cells are unclear. Methods: Inguinal fat pads of green fluorescent protein mice and wild-type mice were cross-transplanted beneath the scalp. At 1, 2, 4, and 12 weeks after transplantation, grafted fat was harvested, weighed, and analyzed through immunohistochemistry, whole-mount staining, and flow cytometry of cell isolates. Bone marrow of green fluorescent protein mice was transplanted to wild-type mice (after irradiation). Eight weeks later, these mice also received fat grafts, which were analyzed as well. Results: The majority of host-derived cells detected during remodeling of grafted fat were macrophages (>90 percent at the early stage; 60 percent at 12 weeks). Cell origins were analyzed at 12 weeks (i.e., when completely regenerated). At this point, mature adipocytes were largely derived from adipose-derived stem/stromal cells of grafts. Although vascular wall constituents were chiefly graft derived, vascular endothelial cells originated equally from graft and host bone marrow. Adipose-derived stem/stromal cells of regenerated fat were an admixture of grafted, host nonbone marrow, and host bone marrow cells. Conclusions: The above findings underscore the importance of adipose stem/stromal cells in the grafted fat for adipocyte regeneration. Host bone marrow and local tissues contributed substantially to capillary networks and provided new adipose-derived stem/stromal cells. An appreciation of mechanisms that are operant in this setting stands to improve clinical outcomes of fat grafting and cell-based therapies.

Mechanical Micronization of Lipoaspirates: Squeeze and Emulsification Techniques.

Background: Condensation of grafted fat has been considered a key for achieving better outcomes after fat grafting. The authors investigated the therapeutic potential of two mechanical tissue micronizing procedures: squeeze and emulsification. Methods: Human aspirated fat was centrifuged (centrifuged fat) and fragmented with an automated slicer (squeezed fat). Alternatively, centrifuged fat was emulsified by repeated transfer between two syringes through a small-hole connecter and then separated by mesh filtration into two portions: residual tissue of emulsified fat and filtrated fluid of emulsified fat. The four products were examined for cellular components. Results: Histologic and electron microscopic analyses revealed that squeezed fat and residual tissue of emulsified fat contained broken adipocytes and fragmented capillaries. Compared with centrifuged fat, the squeezed fat and residual fat products exhibited increased specific gravity and increased numbers of adipose-derived stem/stromal cells and endothelial cells per volume, suggesting successful cell/tissue condensation in both squeezed fat and residual tissue of emulsified fat. Although cell number and viability in the stromal vascular fraction were well maintained in both squeezed fat and residual fat, stromal vascular fraction culture assay showed that adipose-derived stromal cells were relatively damaged in residual tissue of emulsified fat but not in squeezed fat. By contrast, no adipose-derived stromal cells were cultured from filtrated fluid of emulsified fat. Conclusions: The authors’ results demonstrated that mechanical micronization is easily conducted as a minimal manipulation procedure, which can condense the tissue by selectively removing adipocytes without damaging key components, such as adipose-derived stromal cells and endothelial cells. Depending on the extent of adipocyte removal, the product may be a useful therapeutic tool for efficient tissue volumization or therapeutic revitalization/fertilization. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, V.

An injectable non-cross-linked hyaluronic-acid gel containing therapeutic spheroids of human adipose-derived stem cells

For chronic wounds, the delivery of stem cells in spheroidal structures can enhance graft survival and stem cell potency. We describe an easy method for the 3D culture of adipose-derived stem/stromal cells (ASCs) to prepare a ready-to-use injectable. We transferred suspensions of monolayer-cultured ASCs to a syringe containing hyaluronic acid (HA) gel, and then incubated the syringe as a 3D culture vessel. Spheroids of cells formed after 12 h. We found that 6 × 106 ASCs/ml in 3% HA gel achieved the highest spheroid density with appropriate spheroid sizes (20–100 µm). Immunocytology revealed that the stem cell markers, NANOG, OCT3/4, SOX-2, and SSEA-3 were up-regulated in the ASC spheroids compared with those in nonadherent-dish spheroids or in monolayer cultured ASCs. In delayed wound healing mice models, diabetic ulcers treated with ASC spheroids demonstrated faster wound epithelialization with thicker dermis than those treated with vehicle alone or monolayer cultured ASCs. In irradiated skin ulcers in immunodeficient mice, ASC spheroids exhibited faster healing and outstanding angiogenic potential partly by direct differentiation into α-SMA+ pericytes. Our method of 3D in-syringe HA gel culture produced clinically relevant amounts of ready-to-inject human ASC microspheroids that exhibited superior stemness in vitro and therapeutic efficacy in pathological wound repair in vivo.

Micronized cellular adipose matrix as a therapeutic injectable for diabetic ulcer

BACKGROUND Despite the clinical potential of adipose-derived stem/stromal cells (ASCs), there are some clinical difficulties due to the regulation of cell therapies. MATERIALS & METHODS Micronized cellular adipose matrix (MCAM) injectable was prepared through selective extraction of connective tissue fractions in fat tissue only through mechanical minimal manipulation procedures. RESULTS It retained some capillaries and ASCs, but most adipocytes were removed. The presence of viable ASCs, vascular endothelial cells was confirmed and ASCs of MCAM kept intact mesenchymal differentiation capacity. In diabetic mice, skin wounds treated with MCAM showed significantly accelerated healing compared with phosphate-buffered saline-treated ones. CONCLUSION The proven potential of MCAM to accelerate healing in ischemic diabetic ulcers may offer a simple, safe and minimally invasive means for tissue repair and revitalization.

Blood Congestion Can Be Rescued by Hemodilution in a Random-Pattern Skin Flap

Background: There is no standard method to ensure survival of random-pattern skin flaps. The authors developed a rat anemia model to observe survival of random-pattern skin flaps after blood transfusion and hemodilution. Methods: Anemia was induced by withdrawal of 35 percent blood volume followed by compensation with the same amount of blood (blood transfusion model) or plasma equivalent (normovolemic hemodilution). Control rats were subjected to a sham procedure. Subsequently, a random-pattern skin flap (1.5 × 6 cm) was elevated on the back of each rat. Physiologic assessments of flap vascularity/viability were performed using laser Doppler spectrophotometry before and after flap elevation. Results: The normovolemic hemodilution group showed anemia (hemoglobin, 9.5 ± 0.8 g/dl) but less flow occlusion and greater flap survival (72.8 ± 8.6 percent) compared with control (57.4 ± 9.6 percent; p < 0.01) and blood transfusion (62.1 ± 6.5 percent; p < 0.089) groups. In control and blood transfusion groups but not the normovolemic hemodilution group, blood flow was decreased and relative quantity of hemoglobin was increased toward the flap tip, indicating congestion. In control and blood transfusion groups, blood flow and tissue oxygen saturation dropped after flap elevation, but recovered by day 7; congestion gradually improved by day 7. Conclusions: The authors determined that congestion promoted necrosis and hemodilution reduced microcirculatory occlusion and increased blood flow and oxygenation in skin flaps. It was suggested that perioperative hemodilution is superior to blood transfusion in any flap operations unless there is a critical systemic need for blood transfusion.

Pathological changes of adipose tissue in secondary lymphedema

The pathophysiology of lymphoedema is poorly understood. Current treatment options include compression therapy, resection, liposuction and lymphatic microsurgery, but determining the optimal treatment approach for each patient remains challenging.

Cell and Tissue Damage after Skin Exposure to Ionizing Radiation: Short- and Long-Term Effects after a Single and Fractional Doses

Ionizing radiation is often used to treat progressive neoplasms. However, the consequences of long-term radiation exposure to healthy skin tissue are poorly understood. We aimed to evaluate the short- and long-term radiation damage to healthy skin of the same irradiation given either as single or fractional doses. C57BL/J6 mice were randomly assigned to one of three groups: a control and two exposure groups (5 Gy ×2 or 10 Gy ×1). The inguinal area was irradiated (6-MeV beam) 1 week after depilation in the treatment groups. Skin samples were evaluated macroscopically and histologically for up to 6 months after the final exposure. After anagen hair follicle injury by irradiation, hair cycling resumed in both groups, but hair graying was observed in the 10 Gy ×1 group but not in the 5 Gy ×2 group, suggesting the dose of each fractional exposure is more relevant to melanocyte stem cell damage than the total dose. On the other hand, in the long term, the fractional double exposures induced more severe atrophy and capillary reduction in the dermis and subcutis, suggesting fractional exposure may cause more depletion of tissue stem cells and endothelial cells in the tissue. Thus, our results indicated that there were differences between the degrees of damage that occurred as a result of a single exposure compared with fractional exposures to ionizing radiation: the former induces more severe acute injury to the skin with irreversible depigmentation of hairs, while the latter induces long-term damage to the dermis and subcutis.

Perpendicular Strut Injection of Hyaluronic Acid Filler for Deep Wrinkles

Summary: Although various injection techniques of hyaluronic acid (HA) filler for facial rejuvenation have been developed, correction of deep wrinkles/grooves, such as the nasolabial fold (NLF), with intradermal or subdermal injections remains difficult. We tested the intradermal HA injection method to place multiple HA struts by (1) inserting a small needle perpendicularly to the wrinkle and (2) injecting HA as intradermal struts with the skin fully stretched by the practitioner’s fingers. The results of both NLFs in 10 patients suggest that this technique improves NLFs and maintain the effects more consistently than conventional techniques, although the effects of both methods were almost lost after 6 months. Selective and/or combined application of this technique may enhance the current approach to facial rejuvenation with dermal fillers.