Adipose tissue is an extramedullary reservoir for functional hematopoietic stem and progenitor cells. Blood. 2010;115:957-964. [PMID: 19897586 DOI: 10.1182/blood-2009-05-219923]

Combined Use of Autologous Sustained-Release Scaffold of Adipokines and Acellular Adipose Matrix to Construct Vascularized Adipose Tissue

BACKGROUND

Adipose tissue engineering plays a key role in the reconstruction of soft-tissue defects. The acellular adipose matrix (AAM) is a promising biomaterial for the construction of engineered adipose tissue. However, AAM lacks sufficient adipoinduction potency because of the abundant loss of matrix-bound adipokines during decellularization.

METHODS

An adipose-derived extracellular matrix collagen scaffold, "adipose collagen fragment" (ACF), was prepared using a novel mechanical method that provides sustained release of adipokines. Here, the authors used label-free proteomics methods to detect the protein components in AAM and ACF. In vivo, ACF was incorporated into AAM or acellular dermal matrix and implanted into nude mice to evaluate adipogenesis. Neoadipocytes, neovessels, and corresponding gene expression were evaluated. The effects of ACF on adipogenic differentiation of human adipose-derived stem cells and tube formation by human umbilical vein endothelial cells were tested in vitro.

RESULTS

Proteomics analysis showed that ACF contains diverse adipogenic and angiogenic proteins. ACF can release diverse adipokines and induce highly vascularized, mature adipose tissue in AAM, and even in nonadipogenic acellular dermal matrix. Higher expression of adipogenic markers peroxisome proliferator-activated receptor gamma and CCAAT/enhancer-binding protein alpha and greater numbers of tubule structures were observed in ACF-treated groups in vitro.

CONCLUSION

The combination of ACF and AAM could serve as a novel and promising strategy to construct mature, vascularized adipose tissue for soft-tissue reconstruction.

CLINICAL RELEVANCE STATEMENT

The combined use of AAM and ACF has been proven to induce a highly vascularized, mature, engineered adipose tissue in the nude mouse model, which may serve as a promising strategy for soft-tissue reconstruction.

Understanding the interaction between leukaemia stem cells and their microenvironment to improve therapeutic approaches

Although chemotherapeutic regimens can eliminate blasts in leukaemia patients, such therapies are associated with toxicity and often fail to eliminate all malignant cells resulting in disease relapse. Disease relapse has been attributed to the persistence of leukaemia cells in the bone marrow (BM) with the capacity to recapitulate disease; these cells are often referred to as leukaemia stem cells (LSCs). Although LSCs have distinct characteristics in terms of pathobiology and immunophenotype, they are still regulated by their interactions with the surrounding microenvironment. Thus, understanding the interaction between LSCs and their microenvironment is critical to identify effective therapies. To this end, there are numerous efforts to develop models to study such interactions. In this review, we will focus on the reciprocal interactions between LSCs and their milieu in the BM. Furthermore, we will highlight relevant therapies targeting these interactions and discuss some of the promising in vitro models designed to mimic such relationship. LINKED ARTICLES: This article is part of a themed issue on Cancer Microenvironment and Pharmacological Interventions. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v181.2/issuetoc.

Clinical use of autologous adipose-derived stromal vascular fraction cell injections for hip osteoarthritis

Introduction

Currently, studies on adipose-derived stromal vascular fraction (SVF) cells are attracting increasing attention because they have the potential to differentiate into a subset of cell types, such as bone marrow-derived mesenchymal stromal cells (MSCs), and are easier to harvest than MSCs, thus making them easier to apply clinically. This study evaluated the short-term clinical outcomes of SVF cell therapy for hip osteoarthritis (OA).

Methods

Forty-two patients were enrolled in this study; these patients received a single injection comprising an average of 3.8 (standard deviation [SD], ±1.3) × 10⁷ SVF cells into the hip joint. All patients were followed-up for at least 6 months. The mean age of the patients was 60.2 years (SD, ±9.4 years). Kellgren-Lawrence (KL) grades II, III, and IV based on radiography were 13, 13, and 16 patients, respectively. SVF cells were obtained from the subcutaneous fat of the abdomen or breech using a Celution® 800/CRS system. The average cell viability of SVF cells was 90.8% (SD, ±2.8%). Clinical assessments were performed using the Harris Hip Score (HHS), Japanese Orthopaedic Association Hip Disease Evaluation Questionnaire (JHEQ) score, and visual analog scale (VAS) score to evaluate pain. Images were evaluated using radiography, and T2 mapping values were obtained using a 1.5-T magnetic resonance imaging system. These clinical and imaging assessments were followed from preoperatively to 6 months postoperatively.

Results

The HHS, JHEQ score, and VAS score improved significantly from 22.5 (SD, ±16.6), 26.6 (SD, ±11.3), and 75.5 (SD, ±15.8) preoperatively to 46.8 (SD, ±27.2), 39.4 (SD, ±19.7), and 46.5 (SD, ±27.9), respectively, at 6 months postoperatively. KL grade II showed significant improvement in clinical outcome from preoperative to postoperative, while KL grade IV showed slight or little improvement. The center edge angle, acetabular head index on the radiographs, and T2 mapping values did not change significantly from preoperatively to 6 months postoperatively.

Conclusions

SVF cell injection in the hip joint showed good short-term clinical efficacy for reducing hip OA symptoms. SVF cell therapy is thus an innovative and effective treatment for hip OA.

Adipocyte regulation of cancer stem cells

Cancer stem cells (CSCs) are a highly tumorigenic subpopulation of the cancer cells within a tumor that drive tumor initiation, progression, and therapy resistance. In general, stem cell niche provides a specific microenvironment in which stem cells are present in an undifferentiated and self-renewable state. CSC niche is a specialized tumor microenvironment for CSCs which provides cues for their maintenance and propagation. However, molecular mechanisms for the CSC-niche interaction remain to be elucidated. We have revealed that adipsin (complement factor D) and its downstream effector hepatocyte growth factor are secreted from adipocytes and enhance the CSC properties in breast cancers in which tumor initiation and progression are constantly associated with the surrounding adipose tissue. Considering that obesity, characterized by excess adipose tissue, is associated with an increased risk of multiple cancers, it is reasonably speculated that adipocyte-CSC interaction is similarly involved in many types of cancers, such as pancreas, colorectal, and ovarian cancers. In this review, various molecular mechanisms by which adipocytes regulate CSCs, including secretion of adipokines, extracellular matrix production, biosynthesis of estrogen, metabolism, and exosome, are discussed. Uncovering the roles of adipocytes in the CSC niche will propose novel strategies to treat cancers, especially those whose progression is linked to obesity.

Skin mesenchymal niches maintain and protect AML-initiating stem cells

Leukemia cutis or leukemic cell infiltration in skin is one of the common extramedullary manifestations of acute myeloid leukemia (AML) and signifies a poorer prognosis. However, its pathogenesis and maintenance remain understudied. Here, we report massive AML cell infiltration in the skin in a transplantation-induced MLL-AF9 AML mouse model. These AML cells could regenerate AML after transplantation. Prospective niche characterization revealed that skin harbored mesenchymal progenitor cells (MPCs) with a similar phenotype as BM mesenchymal stem cells. These skin MPCs protected AML-initiating stem cells (LSCs) from chemotherapy in vitro partially via mitochondrial transfer. Furthermore, Lama4 deletion in skin MPCs promoted AML LSC proliferation and chemoresistance. Importantly, more chemoresistant AML LSCs appeared to be retained in Lama4-/- mouse skin after cytarabine treatment. Our study reveals the characteristics and previously unrecognized roles of skin mesenchymal niches in maintaining and protecting AML LSCs during chemotherapy, meriting future exploration of their impact on AML relapse.

Analysis of prognostic biomarker models and immune microenvironment in acute myeloid leukemia by integrative bioinformatics

BACKGROUND

Acute myeloid leukemia (AML) is a hematological cancer driven on by aberrant myeloid precursor cell proliferation and differentiation. A prognostic model was created in this study to direct therapeutic care.

METHODS

Differentially expressed genes (DEGs) were investigated using the RNA-seq data from the TCGA-LAML and GTEx. Weighted Gene Coexpression Network Analysis (WGCNA) examines the genes involved in cancer. Find the intersection genes and construct the PPI network to discover hub genes and remove prognosis-related genes. A nomogram was produced for predicting the prognosis of AML patients using the risk prognosis model that was constructed using COX and Lasso regression analysis. GO, KEGG, and ssGSEA analysis were used to look into its biological function. TIDE score predicts immunotherapy response.

RESULTS

Differentially expressed gene analysis revealed 1004 genes, WGCNA analysis revealed 19,575 tumor-related genes, and 941 intersection genes in total. Twelve prognostic genes were found using the PPI network and prognostic analysis. To build a risk rating model, RPS3A and PSMA2 were examined using COX and Lasso regression analysis. The risk score was used to divide the patients into two groups, and Kaplan-Meier analysis indicated that the two groups had different overall survival rates. Univariate and multivariate COX studies demonstrated that risk score is an independent prognostic factor. According to the TIDE study, the immunotherapy response was better in the low-risk group than in the high-risk group.

CONCLUSIONS

We eventually selected out two molecules to construct prediction models that might be used as biomarkers for predicting AML immunotherapy and prognosis.

Arthroscopic Implantation of Adipose-Derived Stromal Vascular Fraction Improves Cartilage Regeneration and Pain Relief in Patients With Knee Osteoarthritis

Purpose

To compare the pain relief and cartilage repair status of patients with knee osteoarthritis who received arthroscopic treatment with or without stromal vascular fraction (SVF) implantation.

Methods

We retrospectively evaluated the patients who were examined with 12-month follow-up magnetic resonance imaging (MRI) after arthroscopic treatment for knee osteoarthritis from September 2019 to April 2021. Patients were included in this study if they had grade 3 or 4 knee osteoarthritis according to the Outerbridge classification in MRI. The visual analog scale (VAS) was used for pain assessment over the follow-up period (baseline and at 1-, 3-, 6-, and 12-month follow-ups). Cartilage repair was evaluated using follow-up MRIs based on Outerbridge grades and the Magnetic Resonance Observation of Cartilage Repair Tissue scoring system.

Results

Among 97 patients who received arthroscopic treatment, 54 patients received arthroscopic treatment alone (conventional group) and 43 received arthroscopic treatment along with SVF implantation (SVF group). In the conventional group, the mean VAS score decreased significantly at 1-month post-treatment compared with baseline (P < .05), and gradually increased from 3 to 12 months' post-treatment (all P < .05). In the SVF group, the mean VAS score decreased until 12 months post-treatment compared with baseline (all P < .05 except P = .780 in 1-month vs 3-month follow-ups). Significantly greater pain relief was reported in the SVF group than in the conventional group at 6 and 12 months' post-treatment (all P < .05). Overall, Outerbridge grades were significantly greater in the SVF group than in the conventional group (P < .001). Similarly, mean Magnetic Resonance Observation of Cartilage Repair Tissue scores were significantly greater (P < .001) in the SVF group (70.5 ± 11.1) than in the conventional group (39.7 ± 8.2).

Conclusions

The results regarding pain improvement and cartilage regeneration and the significant correlation between pain and MRI outcomes at 12-months follow-up indicate that the arthroscopic SVF implantation technique may be useful for repairing cartilage lesions in knee osteoarthritis.

Level of Evidence

Level III, retrospective comparative study.

Adipose-Derived Stromal Vascular Fractions Are Comparable With Allogenic Human Umbilical Cord Blood-Derived Mesenchymal Stem Cells as a Supplementary Strategy of High Tibial Osteotomy for Varus Knee Osteoarthritis

Purpose

To compare the clinical, radiologic, and second-look arthroscopic outcomes of high tibial osteotomy (HTO) with stromal vascular fraction (SVF) implantation versus human umbilical cord blood-derived mesenchymal stem cells (hUCB-MSC) transplantation and identify the association between cartilage regeneration and HTO outcomes.

Methods

Patients treated with HTO for varus knee osteoarthritis between March 2018 and September 2020 were retrospectively identified. In this retrospective study, among 183 patients treated with HTO for varus knee osteoarthritis between March 2018 and September 2020, patients treated with HTO with SVF implantation (SVF group; n = 25) were pair-matched based on sex, age, and lesion size with those who underwent HTO with hUCB-MSC transplantation (hUCB-MSC group; n = 25). Clinical outcomes were evaluated using the International Knee Documentation Committee score and Knee Injury and Osteoarthritis Outcome Score. Radiological outcomes evaluated were the femorotibial angle and posterior tibial slope. All patients were evaluated clinically and radiologically before surgery and during follow-up. The mean final follow-up periods were 27.8 ± 3.6 (range 24-36) in the SVF group and 28.2 ± 4.1 (range, 24-36) in the hUCB-MSC group (P = 0.690). At second-look arthroscopic surgery, cartilage regeneration was evaluated using the International Cartilage Repair Society (ICRS) grade.

Results

A total of 17 male and 33 female patients with a mean age of 56.2 years (range, 49-67 years) were included. At the time of second-look arthroscopic surgery (mean, 12.6 months; range, 11-15 months in the SVF group and 12.7 months; range, 11-14 months in the hUCB-MSC group, P = .625), the mean International Knee Documentation Committee score and Knee Injury and Osteoarthritis Outcome Score in each group significantly improved (P < .001 for all), and clinical outcomes at final follow-up further improved in both groups when compared with the values at second-look arthroscopic surgery (P < .05 for all). Overall ICRS grades, which significantly correlated with clinical outcomes, were similar between groups with no significant differences (P = .170 for femoral condyle and P = .442 for tibial plateau). Radiologic outcomes at final follow-up showed improved knee joint alignment relative to preoperative conditions but showed no significant correlation with clinical outcomes or ICRS grade in either group (P > .05 for all).

Conclusions

Improved clinical and radiological outcomes and favorable cartilage regeneration were seen after surgery for varus Knee OA in both SVF and hUCB-MSC groups.

Level of Evidence

Level III, retrospective comparative study.

Characterization of Human Subcutaneous Adipose Tissue and Validation of the Banking Procedure for Autologous Transplantation

Adipose tissue (AT) is composed of a heterogeneous population which comprises both progenitor and differentiated cells. This heterogeneity allows a variety of roles for the AT, including regenerative functions. In fact, autologous AT is commonly used to repair soft tissue defects, and its cryopreservation could be a useful strategy to reduce the patient discomfort caused by multiple harvesting procedures. Our work aimed to characterize the cryopreserved AT and to validate its storage for up to three years for clinical applications. AT components (stromal vascular fraction-SVF and mature adipocytes) were isolated in fresh and cryopreserved samples using enzymatic digestion, and cell viability was assessed by immunofluorescence (IF) staining. Live, apoptotic and necrotic cells were quantified using cytometry by evaluating phosphatidylserine binding to fluorescent-labeled Annexin V. A multiparametric cytometry was also used to measure adipogenic (CD34+CD90+CD31-CD45-) and endothelial (CD34+CD31+CD45-) precursors and endothelial mature cells (CD34-CD31+CD45-). The maintenance of adipogenic abilities was evaluated using in vitro differentiation of SVF cultures and fluorescent lipid staining. We demonstrated that AT that is cryopreserved for up to three years maintains its differentiation potential and cellular composition. Given our results, a clinical study was started, and two patients had successful transplants without any complications using autologous cryopreserved AT.

A Study on Breast Augmentation Using Fat Grafting With Stromal Vascular Fraction

BACKGROUND

Stromal vascular fraction (SVF) and fat grafting are emerging alternatives to implants for breast augmentation. However, the lack of controlled clinical data has led to conflicting results regarding the effectiveness of surgical treatments. This study aimed to identify the key factors affecting the outcomes of fat grafting with SVF and to recognize novel methods to improve the retention rate.

PATIENTS AND METHODS

In total, 384 women underwent breast augmentation using fat grafting with SVF. The patients were preoperatively and postoperatively managed and recalled for follow-up at 3, 6, and 18 months.

RESULTS

The average volume of the injection in the left breast was 162.35 mL (range, 50-260 mL). The postoperative retention rates were 78.65% in 384 patients at 3 months, 77.17% in 273 patients at 6 months, and 77.48% in 102 patients at 18 months. The retention rates were compared based on the number of SVF cells; patients with more than 60 million cells had a retention rate of 70.77%, and those with less than 60 million cells had a retention rate of 85.60% at 18 months. The retention rates at the 18-month follow-up were 65.62% and 85.09% in stiff and soft breasts, respectively. A higher number of cells in the SVF was associated with a greater retention volume, and the retention volume was greater in patients with soft breasts.Given the higher use of the right arm, after 18 months of the surgery, the retention rate of the right breast (60.35%) was lower than that of the left breast (77.48%) ( P < 0.05; t = -13.199).

CONCLUSIONS

Limiting arm movement, increasing the number of cells in the SVF, and improving the skin tension might enhance the retention rate in patients undergoing breast augmentation.

Adipose tissue and hematopoiesis: Friend or foe?

AIM

Hematopoietic stem cells are the origin of all hematopoietic cells. They have the self-renewal ability and can differentiate into various blood cells. In physiological state, most of the hematopoietic stem cells are dormant, and only a few cells proliferate to maintain hematopoietic homeostasis.

METHODS

This precise steady-state maintenance is regulated by complex mechanisms. Bone marrow adipocytes make up half of all cells in the bone marrow cavity, a feature that has attracted the attention of researchers from multiple fields. The adipocyte density within marrow increases during aging and obesity.

RESULTS

Recent studies have shown that bone marrow adipocytes play important roles in regulating hematopoiesis, but the effects of bone marrow adipocytes on hematopoiesis are often conflicting. Bone marrow adipocytes, participating in the formation of bone marrow hematopoietic microenvironment, influence hematopoiesis positively or negatively. In addition, other adipose tissue, especially white adipose tissue, also regulates hematopoiesis.

CONCLUSION

In this review, we describe the role of adipose tissue in hematological malignancies, which may be useful for understanding hematopoiesis and the pathogenesis of related diseases.

Cartilage lesion size and number of stromal vascular fraction (SVF) cells strongly influenced the SVF implantation outcomes in patients with knee osteoarthritis

PURPOSE

This study evaluated outcomes in patients with knee osteoarthritis following stromal vascular fraction implantation and assessed the associated prognostic factors.

METHODS

We retrospectively evaluated 43 patients who underwent follow-up magnetic resonance imaging 12 months after stromal vascular fraction implantation for knee osteoarthritis. Pain was assessed using the visual analogue scale and measured at baseline and 1-, 3-, 6-, and 12-month follow-up appointments. In addition, cartilage repair was evaluated based on the Magnetic Resonance Observation of Cartilage Repair Tissue scoring system using the magnetic resonance imaging from the 12-month follow-up. Finally, we evaluated the effects of various factors on outcomes following stromal vascular fraction implantation.

RESULTS

Compared to the baseline value, the mean visual analogue scale score significantly and progressively decreased until 12 months post-treatment (P < 0.05 for all, except n.s. between the 1 and 3-month follow-ups). The mean Magnetic Resonance Observation of Cartilage Repair Tissue score was 70.5 ± 11.1. Furthermore, the mean visual analogue scale and Magnetic Resonance Observation of Cartilage Repair Tissue scores significantly correlated 12 months postoperatively (P = 0.002). Additionally, the cartilage lesion size and the number of stromal vascular fraction cells significantly correlated with the 12-month visual analogue scale scores and the Magnetic Resonance Observation of Cartilage Repair Tissue score. Multivariate analyses determined that the cartilage lesion size and the number of stromal vascular fraction cells had a high prognostic significance for unsatisfactory outcomes.

CONCLUSION

Stromal vascular fraction implantation improved pain and cartilage regeneration for patients with knee osteoarthritis. The cartilage lesion size and the number of stromal vascular fraction cells significantly influenced the postoperative outcomes. Thus, these findings may serve as a basis for preoperative surgical decisions.

LEVEL OF EVIDENCE

IV.

Fat Graft Retention: Adipose Tissue, Adipose-Derived Stem Cells, and Aging

SUMMARY

Over the past 30 years, there has been a dramatic increase in the use of autologous fat grafting for soft-tissue augmentation and to improve facial skin quality. Several studies have highlighted the impact of aging on adipose tissue, leading to a decrease of adipose tissue volume and preadipocyte proliferation and increase of fibrosis. Recently, there has been a rising interest in adipose tissue components, including adipose-derived stem/stromal cells (ASCs) because of their regenerative potential, including inflammation, fibrosis, and vascularization modulation. Because of their differentiation potential and paracrine function, ASCs have been largely used for fat grafting procedures, as they are described to be a key component in fat graft survival. However, many parameters as surgical procedures or adipose tissue biology could change clinical outcomes. Variation on fat grafting methods have led to numerous inconsistent clinical outcomes. Donor-to-donor variation could also be imputed to ASCs, tissue inflammatory state, or tissue origin. In this review, the authors aim to analyze (1) the parameters involved in graft survival, and (2) the effect of aging on adipose tissue components, especially ASCs, that could lead to a decrease of skin regeneration and fat graft retention.

CLINICAL RELEVANCE STATEMENT

This review aims to enlighten surgeons about known parameters that could play a role in fat graft survival. ASCs and their potential mechanism of action in regenerative medicine are more specifically described.

Identification of Adipose Tissue as a Reservoir of Macrophages after Acute Myocardial Infarction

Medullary and extra-medullary hematopoiesis has been shown to govern inflammatory cell infiltration and subsequently cardiac remodeling and function after acute myocardial infarction (MI). Emerging evidence positions adipose tissue (AT) as an alternative source of immune cell production. We, therefore, hypothesized that AT could act as a reservoir of inflammatory cells that participate in cardiac homeostasis after MI. To reveal the distinct role of inflammatory cells derived from AT or bone marrow (BM), chimeric mice were generated using standard repopulation assays. We showed that AMI increased the number of AT-derived macrophages in the cardiac tissue. These macrophages exhibit pro-inflammatory characteristics and their specific depletion improved cardiac function as well as decreased infarct size and interstitial fibrosis. We then reasoned that the alteration of AT-immune compartment in type 2 diabetes could, thus, contribute to defects in cardiac remodeling. However, in these conditions, myeloid cells recruited in the infarcted heart mainly originate from the BM, and AT was no longer used as a myeloid cell reservoir. Altogether, we showed here that a subpopulation of cardiac inflammatory macrophages emerges from myeloid cells of AT origin and plays a detrimental role in cardiac remodeling and function after MI. Diabetes abrogates the ability of AT-derived myeloid cells to populate the infarcted heart.

Unraveling the interplay between iron homeostasis, ferroptosis and extramedullary hematopoiesis

Iron participates in myriad processes necessary to sustain life. During the past decades, great efforts have been made to understand iron regulation and function in health and disease. Indeed, iron is associated with both physiological (e.g., immune cell biology and function and hematopoiesis) and pathological (e.g., inflammatory and infectious diseases, ferroptosis and ferritinophagy) processes, yet few studies have addressed the potential functional link between iron, the aforementioned processes and extramedullary hematopoiesis, despite the obvious benefits that this could bring to clinical practice. Further investigation in this direction will shape the future development of individualized treatments for iron-linked diseases and chronic inflammatory disorders, including extramedullary hematopoiesis, metabolic syndrome, cardiovascular diseases and cancer.

Acute Myeloid Leukaemia Drives Metabolic Changes in the Bone Marrow Niche

Acute myeloid leukaemia (AML) is a highly proliferative cancer characterised by infiltration of immature haematopoietic cells in the bone marrow (BM). AML predominantly affects older people and outcomes, particularly in this difficult to treat population remain poor, in part due to inadequate response to therapy, and treatment toxicity. Normal haematopoiesis is supported by numerous support cells within the BM microenvironment or niche, including adipocytes, stromal cells and endothelial cells. In steady state haematopoiesis, haematopoietic stem cells (HSCs) primarily acquire ATP through glycolysis. However, during stress-responses HSCs rapidly transition to oxidative phosphorylation, enabled by mitochondrial plasticity. Historically it was thought that cancer cells preferentially used glycolysis for ATP production, however recently it has become evident that many cancers, including AML primarily use the TCA cycle and oxidative phosphorylation for rapid proliferation. AML cells hijack the stress-response pathways of their non-malignant counterparts, utilising mitochondrial changes to drive expansion. In addition, amino acids are also utilised by leukaemic stem cells to aid their metabolic output. Together, these processes allow AML cells to maximise their ATP production, using multiple metabolites and fuelling rapid cell turnover which is a hallmark of the disease. This review of AML derived changes in the BM niche, which enable enhanced metabolism, will consider the important pathways and discuss future challenges with a view to understanding how AML cells are able to hijack metabolic pathways and how we may elucidate new targets for potential therapies.

Paracrine effect of the stromal vascular fraction containing M2 macrophages on human chondrocytes through the Smad2/3 signaling pathway

The adipose-derived stromal vascular fraction (SVF) is composed of a heterogeneous mix of adipose-derived stem cells (ADSCs), macrophages, pericytes, fibroblasts, blood, and other cells. Previous studies have found that the paracrine effects of SVF cells may be therapeutic, but their role in osteoarthritis treatment remains unclear. This study aimed to investigate the therapeutic effect of SVF cells on chondrocytes. Chondrocytes were seeded on culture plates alone (control) or cocultured with SVF or ADSCs on cell culture inserts. After 48 h of coculture, chondrocyte collagen II, tissue inhibitors of metalloproteinases-3 (TIMP-3), and matrix metalloproteinases-13 (MMP-13) messenger RNA (mRNA) expression levels were evaluated using reverse-transcription polymerase chain reaction, and the transforming growth factor-β (TGF-β) levels in the supernatant were measured using ELISA. Immunohistochemical staining and flow cytometry were used to evaluate the macrophages in the SVF. These macrophages were characterized according to phenotype using the F4/80, CD86, and CD163 markers. To determine whether the Smad2/3 signaling pathways were involved, the chondrocytes were pre-treated with a Smad2/3 phosphorylation inhibitor and stimulated with the SVF, and then Smad2/3 phosphorylation levels were analyzed using western blot. The mRNA expression levels of various paracrine factors and chondrocyte pellet size were also assessed. Collagen II and TIMP-3 expression were higher in the SVF group than in the ADSC group and controls, while MMP-13 expression was the highest in the ADSC group and the lowest in the controls. TGF-β levels in the SVF group were also elevated. Immunohistochemical staining and flow cytometry revealed that the macrophages in the SVF were of the anti-inflammatory phenotype. Western blot analysis showed that the SVF increased Smad2/3 phosphorylation, while Smad2/3 inhibitors decreased phosphorylation. Smad2/3 inhibitors also reduced the expression of various other paracrine factors and decreased chondrocyte pellet size. These findings suggested that the paracrine effect of heterogeneous cells, such as anti-inflammatory macrophages, in the SVF partly supports chondrocyte regeneration through TGF-β-induced Smad2/3 phosphorylation.

CD36-Mediated Fatty Acid Oxidation in Hematopoietic Stem Cells Is a Novel Mechanism of Emergency Hematopoiesis in Response to Infection

Hematopoietic homeostasis depends on the close regulation of hematopoietic stem cell (HSC) activity in the bone marrow. Quiescence and activation in response to stress, among other changes in state, are mediated by shifts in HSC metabolic activity. Although HSC steady-state metabolism is well established, the mechanisms driving HSC activation, proliferation, and differentiation in response to stress remain poorly understood. Here we discuss a study by Mistry et al. that describes a novel metabolic mechanism that fuels HSC activation and expansion. The authors show that to meet their metabolic needs in response to infection, hematopoietic stem and progenitor cells uptake free fatty acids from their microenvironment via CD36 to fuel fatty acid oxidation. These exciting findings suggest that in the context of infection, HSCs undergo a metabolic shift toward fatty acid metabolism that drives emergency hematopoiesis and raise questions about the role of the microenvironment in this process.

Molecular Systems Architecture of Interactome in the Acute Myeloid Leukemia Microenvironment

A molecular systems architecture is presented for acute myeloid leukemia (AML) to provide a framework for organizing the complexity of biomolecular interactions. AML is a multifactorial disease resulting from impaired differentiation and increased proliferation of hematopoietic precursor cells involving genetic mutations, signaling pathways related to the cancer cell genetics, and molecular interactions between the cancer cell and the tumor microenvironment, including endothelial cells, fibroblasts, myeloid-derived suppressor cells, bone marrow stromal cells, and immune cells (e.g., T-regs, T-helper 1 cells, T-helper 17 cells, T-effector cells, natural killer cells, and dendritic cells). This molecular systems architecture provides a layered understanding of intra- and inter-cellular interactions in the AML cancer cell and the cells in the stromal microenvironment. The molecular systems architecture may be utilized for target identification and the discovery of single and combination therapeutics and strategies to treat AML.

The Effect of Autologous Adipose-Derived Stromal Vascular Fractions on Cartilage Regeneration Was Quantitatively Evaluated Based on the 3D-FS-SPGR Sequence: A Clinical Trial Study

Background

Numerous reports confirmed the safety and clinical efficacy of autologous adipose-derived stromal vascular fractions (SVF), which have recently been used to treat osteoarthritis (OA). However, there is still no consensus as to whether SVF can promote cartilage regeneration. Herein, the purpose of our study was to evaluate the effectiveness of SVF versus hyaluronic acid (HA) in cartilage regeneration by establishing a cartilage model based on the three-dimensional fat-suppressed spoiled gradient recalled echo (3D-FS-SPGR) sequence.

Methods

Patients with symptomatic OA were recruited in our research, who were randomized into two groups. Meanwhile, patients in Kellgren-Lawrence (K-L) grades 2 and 3 were distinguished in each group. In the test group, patients received SVF injections of the knee, while patients in the control group received the same dose of HA. Each patient underwent the 3D-FS-SPGR sequence to establish a cartilage model at baseline, 6 months, and 12 months, respectively. The cartilage was characterized into six regions, and relevant parameters of the cartilage model were counted. Clinical and radiographic scores were recorded in one-year follow-up.

Results

In all regions, the thickness and volume of cartilage defect and the volume of healthy cartilage were improved to some extent in the test group, especially the medial femoral condyle (MF) and medial tibial condyle (MT). In grades 2 and 3, the thickness and volume of cartilage defect decreased by 0.92 ± 0.18 mm and 1.03 ± 0.23 mm and 84.00 ± 32.30 mm³ and 130.30 ± 49.56 mm³ in MF and by 0.96 ± 0.22 mm and 0.99 ± 0.14 mm and 64.18 ± 21.40 mm³ and 95.11 ± 19.93 mm³ in MT, respectively. No such phenomenon was observed in the control group. Meanwhile, the SVF-treated knees showed significant improvement in clinical and radiographic scores at 12 months. Nevertheless, these scores of the control group became worse at 12-month follow-up visit.

Conclusion

Taken together, this study shows that intra-articular injection of SVF markedly improved the clinical symptoms without adverse events, thereby repairing the damaged articular cartilage through cartilage regeneration.

Food and Drug Administration's Position on Commonly Injected Biologic Materials in Orthopaedic Surgery

The use of biologically based therapies is becoming a popular less-invasive therapy for relieving pain and promoting tissue regeneration. The most commonly used biologics are autologous adipose-derived products, bone marrow aspirations, and platelet-rich plasma (PRP). Birth tissue is a common allogenic source of biologics, including umbilical cord, placental membranes, and amniotic fluid. Injected biologics, depending on the indication and how they are processed, formulated, delivered, and promoted, can be subject to different regulatory pathways. The aim of this review is to provide an overview of these products and procedures and educate the musculoskeletal community about the relevant current Food and Drug Administration (FDA) regulations.

Influence of the mesenchymal stromal cell source on the hematopoietic supportive capacity of umbilical cord blood-derived CD34+-enriched cells

Background

Umbilical cord blood (UCB) is a clinically relevant alternative source of hematopoietic stem/progenitor cells (HSPC). To overcome the low cell number per UCB unit, ex vivo expansion of UCB HSPC in co-culture with mesenchymal stromal cells (MSC) has been established. Bone marrow (BM)-derived MSC have been the standard choice, but the use of MSC from alternative sources, less invasive and discardable, could ease clinical translation of an expanded CD34⁺ cell product. Here, we compare the capacity of BM-, umbilical cord matrix (UCM)-, and adipose tissue (AT)-derived MSC, expanded with/without xenogeneic components, to expand/maintain UCB CD34⁺-enriched cells ex vivo.

Methods

UCB CD34⁺-enriched cells were isolated from cryopreserved mononuclear cells and cultured for 7 days over an established feeder layer (FL) of BM-, UCM-, or AT-derived MSC, previously expanded using fetal bovine serum (FBS) or fibrinogen-depleted human platelet lysate (HPL) supplemented medium. UCB cells were cultured in serum-free medium supplemented with SCF/TPO/FLT3-L/bFGF. Fold increase in total nucleated cells (TNC) as well as immunophenotype and clonogenic potential (cobblestone area-forming cells and colony-forming unit assays) of the expanded hematopoietic cells were assessed.

Results

MSC from all sources effectively supported UCB HSPC expansion/maintenance ex vivo, with expansion factors (in TNC) superior to 50x, 70x, and 80x in UCM-, BM-, and AT-derived MSC co-cultures, respectively. Specifically, AT-derived MSC co-culture resulted in expanded cells with similar phenotypic profile compared to BM-derived MSC, but resulting in higher total cell numbers. Importantly, a subpopulation of more primitive cells (CD34⁺CD90⁺) was maintained in all co-cultures. In addition, the presence of a MSC FL was essential to maintain and expand a subpopulation of progenitor T cells (CD34⁺CD7⁺). The use of HPL to expand MSC prior to co-culture establishment did not influence the expansion potential of UCB cells.

Conclusions

AT represents a promising alternative to BM as a source of MSC for co-culture protocols to expand/maintain HSPC ex vivo. On the other hand, UCM-derived MSC demonstrated inferior hematopoietic supportive capacity compared to MSC from adult tissues. Despite HPL being considered an alternative to FBS for clinical-scale manufacturing of MSC, further studies are needed to determine its impact on the hematopoietic supportive capacity of these cells.

ILC2s Improve Glucose Metabolism Through the Control of Saturated Fatty Acid Absorption Within Visceral Fat

Background and aims

Group 2 innate lymphoid cells (ILC2s) have been implicated in the regulation of metabolic homeostasis in mice.

Methods

In this study, the role of ILC2s in white adipose tissue (WAT) was investigated using ST2, an IL-33 receptor that is expressed on ILC2 knockout mice.

Results

The deficiency of ST2 decreased ILC2s in WAT, whereas ex-ILC2, which acquired group 1 innate lymphoid cell (ILC1)-like traits, was increased. This led to significant metabolic disorders such as visceral fat obesity, decreased browning in WAT, reduction of energy metabolism, and impaired glucose tolerance, compared to wild type (WT) mice. Those metabolic abnormalities of ST2-knockout (ST2KO) mice were not ameliorated by IL-33 administration, but impaired glucose tolerance and visceral fat obesity were significantly improved by transplantation of ILCs from the bone marrow of WT mice. The relative expression of Cd36 in WAT increased due to the deficiency of ST2, and the storage of saturated fatty acids in WAT of ST2KO mice was significantly higher than that of WT mice. Moreover, saturated fatty acids aggravated the chronic inflammation in adipocytes, promoted the differentiation of M1-like macrophages, and inhibited that of M2-like macrophages.

Conclusions

Our results indicated that ILC2 regulates diet-induced obesity and chronic inflammation through the regulation of saturated fatty acid absorption in visceral adipose tissue.

Erythritol Ameliorates Small Intestinal Inflammation Induced by High-Fat Diets and Improves Glucose Tolerance

BACKGROUND

Erythritol, a sugar alcohol, is widely used as a substitute for sugar in diets for patients with diabetes or obesity.

METHODS

In this study, we aimed to investigate the effects of erythritol on metabolic disorders induced by a high-fat diet in C57BL/6J mice, while focusing on changes in innate immunity.

RESULTS

Mice that were fed a high-fat diet and administered water containing 5% erythritol (Ery group) had markedly lower body weight, improved glucose tolerance, and markedly higher energy expenditure than the control mice (Ctrl group) (n = 6). Furthermore, compared with the Ctrl group, the Ery group had lesser fat deposition in the liver, smaller adipocytes, and significantly better inflammatory findings in the small intestine. The concentrations of short-chain fatty acids (SCFAs), such as acetic acid, propanoic acid, and butanoic acid, in the serum, feces, and white adipose tissue of the Ery group were markedly higher than those in the Ctrl group. In flow cytometry experiments, group 3 innate lymphoid cell (ILC3) counts in the lamina propria of the small intestine and ILC2 counts in the white adipose tissue of the Ery group were markedly higher than those in the Ctrl group. Quantitative real-time reverse transcription polymerase chain reaction analyses showed that the Il-22 expression in the small intestine of the Ery group was markedly higher than that in the Ctrl group.

CONCLUSIONS

Erythritol markedly decreased metabolic disorders such as diet-induced obesity, glucose intolerance, dyslipidemia, and fat accumulation in the mouse liver by increasing SCFAs and modulating innate immunity.

Vascular Regenerative Capacity and the Obesity Paradox in Coronary Artery Disease

[Figure: see text].

The effect of a fibroblast growth factor, insulin-like growth factor, growth hormone, and Biolaminin 521 LN on the proliferative activity of cat stem cells

The wide use of cell technologies in clinical practice requires a large amount of cell material, which has led to improvement in culture conditions, making it possible to obtain more cell material in a shorter period of time. Thus, the purpose of our paper was to study the effects of different concentrations of an insulin-like growth factor (IGF-1), a fibroblast growth factor (FGF-2),| a growth hormone (rhGH), and Biolaminin 521 LN (LN 521) on the proliferative activity and genetic stability of stem cell cultures derived from the cat bone marrow, adipose tissue, and myocardium. Cell cultures for the experiment were obtained from the adipose tissue, bone marrow, and myocardium of a cat. Differences were found in the effects of the various growth promoters on the proliferative activity of cells in the culture. The IGF-1 demonstrated a positive effect on the proliferative activity of all cultures. The addition of the rhGH to the bone marrow-derived cell culture increased the size of the cells and decreased the proliferation index relative to the control group. The addition of the growth factors to the culture medium did not significantly increase the number of cells with altered karyotype in any of the cultures relative to the control group.

Combination of platelet rich plasma and stromal vascular fraction on the level of vascular endothelial growth factor in rat subjects experiencing deep dermal burn injury

Background

The healing process of burns includes coagulation, inflammation, and remodeling. Vascular endothelial growth factor (VEGF) is involved throughout this healing process. Stem cells from the platelet-rich plasma (PRP) with stromal vascular fraction (SVF) can increase concentrations of growth factors, including VEGF. This is expected to accelerate burn healing. The aim of this study was to determine the effect of a combination of PRP and SVF on VEGF levels in a rats model of deep dermal burn wound healing.

Materials and methods

This is an experimental research study in rats using a post-test control group design with 4 groups: A) control, B) Vaseline, C) topical PRP and SVF, and D) PRP and SVF injection. Burn wounds were induced according to the modified Guo method.

Results

In a rats model of deep dermal wound healing, topical Vaseline significantly increased serum VEGF compared to control. Topical application and injection of stem cells also significantly increased serum VEGF compared to control and Vaseline. The VEGF concentration was significantly higher following injection of PRP and SVF, suggesting that the injection route is more effective at increasing VEGF levels compared to the topical application of stem cells.

Conclusion

The combination of PRP and SVF, either by injection or topical application, can increase VEGF levels during the healing process from deep dermal burns.

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Stem cells can increase concentrations of growth factors.

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Topical application and injection of stem cells significantly increased serum VEGF compared to control.

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The VEGF concentration was significantly higher following injection of PRP and SVFs.

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The injection route of stem cells is more effective at increasing VEGF levels compared to the topical application.

Allogeneic adipose-derived stem cells mitigate acute radiation syndrome by the rescue of damaged bone marrow cells from apoptosis

Acute radiation syndrome (ARS) is the radiation toxicity that can affect the hematopoietic, gastrointestinal, and nervous systems upon accidental radiation exposure within a short time. Currently, there are no effective and safe approaches to treat mass population exposure to ARS. Our study aimed to evaluate the therapeutic potential of allogeneic adipose‐derived stem cells (ASCs) for total body irradiation (TBI)‐induced ARS and understand the underlying mitigation mechanism. We employed 9.25 Gy TBI dose to C57BL/6 mice and studied the effect of allogeneic ASCs on mice survival and regeneration of the hematopoietic system. Our results indicate that intraperitoneal‐injected ASCs migrated to the bone marrow, rescued hematopoiesis, and improved the survival of irradiated mice. Our transwell coculture results confirmed the migration of ASCs to irradiated bone marrow and rescue hematopoietic activity. Furthermore, contact coculture of ASCs improved the survival and hematopoiesis of irradiated bone marrow in vitro. Irradiation results in DNA damage, upregulation of inflammatory signals, and apoptosis in bone marrow cells, while coculture with ASCs reduces apoptosis via activation of DNA repair and the antioxidation system. Upon exposure to irradiated bone marrow cells, ASCs secrete prosurvival and hematopoietic factors, such as GM‐CSF, MIP1α, MIP1β, LIX, KC, 1P‐10, Rantes, IL‐17, MCSF, TNFα, Eotaxin, and IP‐10, which reduces oxidative stress and rescues damaged bone marrow cells from apoptosis. Our findings suggest that allogeneic ASCs therapy is effective in mitigating TBI‐induced ARS in mice and may be beneficial for clinical adaptation to treat TBI‐induced toxicities. Further studies will help to advocate the scale‐up and adaptation of allogeneic ASCs as the radiation countermeasure.

Shorter Interdonation Interval Contributes to Lower Cell Counts in Subsequent Stem Cell Donations

Approximately 7% of unrelated hematopoietic stem cell donors are asked to donate stem cells a subsequent time to the same or a different recipient. Recent studies have shown that donation-related symptoms for second donations are similar to those for the first donation. Little is known about differences in stem cell mobilization and yields for subsequent peripheral blood stem cell (PBSC) and bone marrow (BM) collections. We hypothesized that CD34⁺ cell yields and total nucleated cell (TNC) concentrations for subsequent PBSC or BM donations are lower than those at the first donation. We also evaluated the factors influencing stem cell yields in healthy unrelated second-time donors. Data were gathered from the Center for International Blood and Marrow Transplant Research database on 513 PBSC and 43 BM donors who donated a second time between 2006 and 2017 through the National Marrow Donor Program. Among the second-time PBSC donors, we found significantly lower preapheresis peripheral blood CD34⁺ cell counts (68.6 × 10⁶/L versus 73.9 × 10⁶/L; P = .03), and collection yields (556 × 10⁶ versus 608 × 10⁶; P = .02) at the second donation compared to the first. This decrease at the subsequent donation was associated with a shorter interdonation interval, lower body mass index (BMI), and a lower total G-CSF dose. In most instances, suboptimal mobilizers at their first donation donated suboptimal numbers of stem cells at their subsequent donations. Among repeat BM donors, the TNC concentration was lower at the second donation. The small size of this group precluded additional analysis. Overall, when considering repeat donations, increasing the interdonation intervals and evaluating for BMI changes should be considered to optimize stem cell yields. Some of these parameters may be improved by increasing G-CSF dose in PBSC donors within permissible limits.

Single-cell RNA sequencing reveals the induction of novel myeloid and myeloid-associated cell populations in visceral fat with long-term obesity

Macrophages and other immune cells are important contributors to obesity-associated inflammation; however, the cellular identities of these specific populations remain unknown. In this study, we identified individual populations of myeloid cells found in mouse epididymal/visceral adipose tissue by single-cell RNA sequencing, immunofluorescence, and flow cytometry. Multiple canonical correlation analysis identified 11 unique myeloid and myeloid-associate cell populations. In obese mice, we detected an increased percentage of monocyte-derived pro-inflammatory cells expressing Cd9 and Trem2, as well as significantly decreased percentages of multiple cell populations, including tissue-resident cells expressing Lyve1, Mafb, and Mrc1. We have identified and validated a novel myeloid/macrophage population defined by Ly6a expression, exhibiting both myeloid and mesenchymal characteristics, which increased with obesity and showed high pro-fibrotic characteristics in vitro. Our mouse adipose tissue myeloid cell atlas provides an important resource to investigate obesity-associated inflammation and fibrosis.

Remodeling of Bone Marrow Niches and Roles of Exosomes in Leukemia

Leukemia is a hematological malignancy that originates from hematopoietic stem cells in the bone marrow. Significant progress has made in understanding its pathogensis and in establishing chemotherapy and hematopoietic stem cell transplantation therapy (HSCT). However, while the successive development of new therapies, such as molecular-targeted therapy and immunotherapy, have resulted in remarkable advances, the fact remains that some patients still cannot be saved, and resistance to treatment and relapse are still problems that need to be solved in leukemia patients. The bone marrow (BM) niche is a microenvironment that includes hematopoietic stem cells and their supporting cells. Leukemia cells interact with bone marrow niches and modulate them, not only inducing molecular and functional changes but also switching to niches favored by leukemia cells. The latter are closely associated with leukemia progression, suppression of normal hematopoiesis, and chemotherapy resistance, which is precisely the area of ongoing study. Exosomes play an important role in cell-to-cell communication, not only with cells in close proximity but also with those more distant due to the nature of exosomal circulation via body fluids. In leukemia, exosomes play important roles in leukemogenesis, disease progression, and organ invasion, and their usefulness in the diagnosis and treatment of leukemia has recently been reported. The interaction between leukemia cell-derived exosomes and the BM microenvironment has received particular attention. Their interaction is believed to play a very important role; in addition to their diagnostic value, exosomes could serve as a marker for monitoring treatment efficacy and as an aid in overcoming drug resistance, among the many problems in leukemia patients that have yet to be overcome. In this paper, we will review bone marrow niches in leukemia, findings on leukemia-derived exosomes, and exosome-induced changes in bone marrow niches.

Cryopreserved human adipose-derived stromal vascular fraction maintains fracture healing potential via angiogenesis and osteogenesis in an immunodeficient rat model

Background

Novel therapeutic strategies for the healing of nonunion, which has serious effects on the quality of life of patients, are needed. We evaluated the therapeutic effect of local transplantation of human stromal vascular fraction (SVF) cells on fracture healing in a rat non-healing fracture model and compared the effects between freshly isolated (F) and cryopreserved (C)-SVFs.

Methods

Non-healing fracture model was induced in the femur of female immunodeficient rats (F344/N Jcl rnu/rnu) with cauterizing periosteum. Immediately after the creation of non-healing fracture, rats received local transplantation of F and C-SVFs suspended in phosphate-buffered saline (PBS) or the same volume of PBS without cells using the same scaffold as a control group. During 8 weeks post-surgery, radiologic, histological, immunohistochemical, and biomechanical analyses were performed to evaluate fracture healing. The comparison of radiological results was performed with a chi-square test, and the multiple comparisons of immunohistochemical, histological, and biomechanical results among groups were made using a one-way analysis of variance. A probability value of 0.05 was considered to denote statistical significance.

Results

At week 8, in 60% of animals receiving F-SVF cells and in 50% of animals receiving C-SVF cells, the fracture radiologically healed with bone union whereas nonunion was observed in the control group. The healing potential was also confirmed by histological and biomechanical assessments. One of the mechanisms underlying healing involving intrinsic angiogenesis/osteogenesis was enhanced in F- and C-SVF groups compared with that in the control group. Human cell-derived vasculogenesis/osteogenesis, which was also confirmed in an in vitro differentiation assay, was also enhanced in the F- and C-SVF groups compared with that in the control groups and could be another mechanism for healing.

Conclusions

SVF cells can enhance bone healing and cryopreserved cells have almost equal potential as fresh cells. SVF cells can be used for improving nonunion bone fracture healing as an alternative to other mesenchymal stem cells and the effect of SVF cells can be maintained under cryopreservation.

Comparison of Clinical and Imaging Outcomes of Different Doses of Adipose-Derived Stromal Vascular Fraction Cell Treatment for Knee Osteoarthritis

Favorable clinical outcomes of intra-articular injection of adipose-derived stromal vascular fraction (SVF) cells for knee osteoarthritis (OA) have been reported, but the effects of different doses of SVF cells have not been examined. This study aimed to compare the short-term clinical and imaging outcomes of different doses of SVF cells for knee OA treatment. This study included 60 patients with knee OA who underwent intra-articular injection of SVF cells. The follow-up period was at least 12 months. Thirty patients received an intra-articular injection of 2.5×10⁷ SVF cells (low-dose group), and the remaining 30 patients received an intra-articular injection of 5.0×10⁷ SVF cells (high-dose group). Clinical evaluations were performed for the Knee injury and Osteoarthritis Outcome Score (KOOS). Imaging evaluations, including the magnetic resonance imaging Osteoarthritis Knee Score (MOAKS) features (bone marrow lesions, cartilage defects, osteophytes, Hoffa’s synovitis, and effusion synovitis), were also performed. All clinical and imaging evaluations were performed preoperatively and 12 months postoperatively and compared between the groups. In demographic data, no significant differences were found between the two groups. The total score of KOOS at 12 months postoperatively was significantly more favorable than the preoperative score in the high-dose groups. Pain and symptoms subscale scores of KOOS at 12 months postoperatively were significantly better in the high-dose group than in the low-dose group. The bone marrow lesions, Hoffa’s synovitis, and effusion synovitis improved approximately 30–40% at 12 months postoperatively compared to baseline in both groups. However, there were no significant differences in imaging evaluations between the two groups. In conclusion, the pain and symptoms subscale scores of KOOS from baseline to 12 months postoperatively improved better in the high-dose group than in the low-dose group. Our findings suggest that intra-articular injection of SVF cells for knee OA is an innovative approach.

Immediate fat and nanofat-enriched fat grafting in breast reduction for scar management

BACKGROUND

Reduction mammoplasty can be successful but surgical scars may continue to be a most undesirable and unavoidable outcome. Various medical and non-invasive methods are available to minimize scar formation but as yet no methods have been discovered to eliminate them. We hypothesize that immediate fat and nanofat-enriched fat graft transfer may improve the scar quality and optimize results.

MATERIALS AND METHODS

This prospective study comprised 45 superomedial pedicle wise-pattern breast reduction patients divided into three groups of 15 in a randomized fashion. The control group had no additional injections whereas the other two groups received injections of fat and nanofat-enriched fat grafts immediately under their surgery scars, respectively. Surgical scar formation was evaluated at six months and scars were scored using the Vancouver scar scale and a visual analogue scale.

RESULTS

Fat and nanofat-enriched fat graft-injected groups scored significantly better on all items of the Vancouver scar scale, except for scar height, compared to the control group (p < 0.05). Visual analogue scores were significantly lower in the fat and nanofat-enriched fat graft-injected groups compared to the control group (p < 0.05).

CONCLUSIONS

In breast reduction patients, simultaneous fat and nanofat-enriched fat grafting appears to be a safe and promising strategy for scar management.

Salsalate reverses metabolic disorders in a mouse model of non-alcoholic fatty liver disease through AMPK activation and caspase-6 activity inhibition

Salsalate, an ester formed by 2 salicylic acid molecules, has beneficial effect against metabolic disorders in clinical trials and in animal studies. This study focused on the mechanistic aspects of salsalate activity against non-alcoholic fatty liver disease (NAFLD). Using high-fat diet (HFD) fed mice, we showed that salsalate treatment decreased body-weight gains, reduced white adipose tissue mass and improved glycaemic control. Mice in salsalate-treated group also had reduced obese adipose tissue and hepatic macrophage infiltration and inflammation and adipogenesis gene expression. Histology analysis revealed predominant decreases in hepatosteatosis, including both macrovesicular and microvesicular steatoses. The treatment reversed AMPK activity repression that was accompanied by reduced caspase-6 activity and cleavage. Enzymatic assay and cell culture studies showed that salsalate promoted AMPK activation by directly activating AMPK. This study links salsalate effect against metabolic disorders to its activity on reversion of AMPK repression in NAFLD mice and on suppression of adipogenic gene induction.

Contribution of Extramedullary Hematopoiesis to Atherosclerosis. The Spleen as a Neglected Hub of Inflammatory Cells

Cardiovascular diseases (CVDs) incidence is becoming higher. This fact is promoted by metabolic disorders such as obesity, and aging. Atherosclerosis is the underlying cause of most of these pathologies. It is a chronic inflammatory disease that begins with the progressive accumulation of lipids and fibrotic materials in the blood-vessel wall, which leads to massive leukocyte recruitment. Rupture of the fibrous cap of the atherogenic cusps is responsible for tissue ischemic events, among them myocardial infarction. Extramedullary hematopoiesis (EMH), or blood cell production outside the bone marrow (BM), occurs when the normal production of these cells is impaired (chronic hematological and genetic disorders, leukemia, etc.) or is altered by metabolic disorders, such as hypercholesterolemia, or after myocardial infarction. Recent studies indicate that the main EMH tissues (spleen, liver, adipose and lymph nodes) complement the hematopoietic function of the BM, producing circulating inflammatory cells that infiltrate into the atheroma. Indeed, the spleen, which is a secondary lymphopoietic organ with high metabolic activity, contains a reservoir of myeloid progenitors and monocytes, constituting an important source of inflammatory cells to the atherosclerotic lesion. Furthermore, the spleen also plays an important role in lipid homeostasis and immune-cell selection. Interestingly, clinical evidence from splenectomized subjects shows that they are more susceptible to developing pathologies, such as dyslipidemia and atherosclerosis due to the loss of immune selection. Although CVDs represent the leading cause of death worldwide, the mechanisms involving the spleen-atherosclerosis-heart axis cross-talk remain poorly characterized.

Adipocytes in hematopoiesis and acute leukemia: friends, enemies, or innocent bystanders?

The bone marrow is home to well-balanced normal hematopoiesis, but also the stage of leukemia's crime. Marrow adipose tissue (MAT) is a unique and versatile component of the bone marrow niche. While the importance of MAT for bone health has long been recognized, its complex role in hematopoiesis has only recently gained attention. In this review article we summarize recent conceptual advances in the field of MAT research and how these developments impact our understanding of MAT regulation of hematopoiesis. Elucidating routes of interaction and regulation between MAT and cells of the hematopoietic system are essential to pinpoint vulnerable processes resulting in malignant transformation. The concept of white adipose tissue contributing to cancer development and progression on the cellular, metabolic, and systemic level is generally accepted. The role of MAT in malignant hematopoiesis, however, is controversial. MAT is very sensitive to changes in the patient's metabolic status hampering a clear definition of its role in different clinical situations. Here, we discuss future directions for leukemia research in the context of metabolism-induced modifications of MAT and other adipose tissues and how this might impact on leukemia cell survival, proliferation, and antileukemic therapy.

Isolation of mesenchymal stem cells from Pap smear samples

Objective

Exploiting their ability to differentiate into mesenchymal lineages like cartilage, bone, fat, and muscle, and to elicit paracrine effects, mesenchymal stem cells (MSCs) are widely used in clinical settings to treat tissue injuries and autoimmune disorders. One of accessible sources of MSC is the samples used for Papanicolaou (Pap) test, which is a cervical screening method for detecting potentially pre-cancerous and cancerous alterations in the cervical cells and to diagnose genetic abnormalities in fetuses. This study aimed to identify and isolate the stem cells from Pap smear samples collected from pregnant women, and to trace the origin of these cells to maternal or fetal tissue, and characterize their stem cell properties.

Methods

To investigate the possibility and efficiency of establishing MSC lines from the Pap smear samples, we were able to establish 6 cell lines from Pap smear samples from 60 pregnant women at different stages of gestation.

Results

The 3 cell lines randomly selected among the 6 established in this study, displayed high proliferation rates, several characteristics of MSCs, and the capacity to differentiate into adipocytes, osteocytes, and chondrocytes. Our study identified that the stem cell lines obtainable from Pap smear sampling were uterine cervical stromal cells (UCSCs) and had 10% efficiency of establishment.

Conclusion

Despite their low efficiency of establishment, human UCSCs from Pap smear samples can become a simple, safe, low-cost, and donor-specific source of MSCs for stem cell therapy and regenerative medicine.

Markers of Regenerative Processes in Patients with Bipolar Disorder: A Case-control Study

Progress in medical science has allowed the discovery of many factors affecting the pathogenesis of bipolar disorder, and among the most recent research directions are found regenerative and inflammatory processes. The role of regenerative processes remains particularly poorly explored, but available data encourage further research, which may explain the pathogenesis of bipolar disorder (BD). The aim of this study was to evaluate the mobilization of stem cells into peripheral blood, in patients with bipolar disorder during stable phase, not treated with lithium salts. The study included 30 unrelated individuals with the diagnosis of bipolar disorder, with disease duration of at least 10 years, not treated with lithium salts for at least five years prior to the study. The control group consisted of 30 healthy subjects, matched for age, sex, body mass index (BMI), origin, socio-demographic factors and nicotine use. Blood samples underwent cytometric analyses to assess concentrations of: Very Small Embryonic Like (VSEL) CD34+, VSEL AC133+, HSC CD34+, HSC AC133+. There were no significant differences in stem cell levels between patients with BD and healthy controls. However, the level of VSEL cells AC133 + was significantly higher in type I BD patients compared to healthy controls. Our results indicate a disturbance in regenerative processes in patients with bipolar disorder.

The influence of adipose-derived stromal vascular fraction cells on the treatment of knee osteoarthritis

Background

Adipose-derived stromal vascular fraction (SVF) cells are a mixed cell population that includes cells with multilineage potential, similar to bone marrow-derived mesenchymal stem cells. Our purpose is to investigate the influence of SVF cells in patients with knee osteoarthritis (OA) and the short-term treatment effects.

Methods

Fifty-seven patients were enrolled and treated with intra-articular injection of 2.5 × 10⁷ SVF cells into the knee joint between September 2017 and March 2018. All patients were followed up for 12 months or longer. Mean age at treatment and follow-up period were 69.4 ± 6.9 years and 13.7 ± 2.0 months, respectively. The mean preoperative hip-knee-ankle angle was 6.7 ± 3.6°. SVF cells were prepared using the Celution®800/CRS system from the patients’ abdominal or breech subcutaneous fat. The mean SVF cell viability was 90.6 ± 2.7%. Clinical evaluations were performed for range of motion, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), visual analog scale (VAS) for pain, and the Knee injury and Osteoarthritis Score (KOOS). Imaging evaluations, which included the hip-knee-ankle angle assessed via radiography, and T2 mapping value using a 1.5-T magnetic resonance imaging unit were also assessed. Both clinical and imaging evaluations were performed preoperatively, 1, 3, 6, and 12 months postoperatively, and compared among all timepoints (p < 0.05).

Results

Knee extension angle at 6 and 12 months postoperatively was significantly better than the preoperative angle. Total WOMAC, VAS, and KOOS scores at 1, 3, 6 and 12 months postoperatively were significantly better than preoperative scores. There was no significant difference in hip-knee-ankle angle among the five time periods. T2 mapping values of lateral femur and tibia were significantly higher 12 months postoperatively than preoperatively.

Conclusions

The short-term clinical effects of intra-articular SVF cell injection on knee OA were excellent. Intra-articular SVF cell injection is a novel and innovative approach for treating patients with knee OA.

Acute Myeloid Leukaemia in Its Niche: the Bone Marrow Microenvironment in Acute Myeloid Leukaemia

Purpose of Review

Acute myeloid leukaemia (AML) is a heterogeneous malignancy for which treatment options remain suboptimal. It is clear that a greater understanding of the biology of the AML niche will enable new therapeutic strategies to be developed in order to improve treatment outcomes for patients.

Recent Findings

Recent evidence has highlighted the importance of the bone marrow microenvironment in protecting leukaemia cells, and in particular leukaemic stem cells from chemotherapy-induced cell death. This includes mesenchymal stem cells supporting growth and preventing apoptosis, and altered action and secretion profiles of other niche components including adipocytes, endothelial cells and T cells.

Summary

Here, we provide a detailed overview of the current understanding of the AML bone marrow microenvironment. Clinical trials of agents that mobilise leukaemic stem cells from the bone marrow are currently ongoing and show early promise. Future challenges will involve combining these novel therapies targeted at the AML niche with conventional chemotherapy treatment.

Micro Fragmented Adipose Tissue Promotes the Matrix Synthesis Function of Nucleus Pulposus Cells and Regenerates Degenerated Intervertebral Disc in a Pig Model

Intervertebral disc (IVD) degeneration and consequent lower back pain is a common disease. Micro fragmented adipose tissue (MFAT) is promising for a wide range of applications in regenerative medicine. In this study, MFAT was isolated by a nonenzymatic method and co-cultured with nucleus pulposus cells (NPCs) using an indirect co-culture system in vitro. A pig disc degeneration model was used to investigate the regenerative effect of MFAT on degenerated IVDs in vivo. The mRNA expression of Sox9, Acan, and Col2 in NPCs was significantly increased, while no significant increase was observed in the mRNA expression of proinflammatory cytokine genes after the NPCs were co-cultured with MFAT. Nucleus pulposus (NP)-specific markers were increased in MFAT cells after co-culture with NPCs. After injection of MFAT, the disc height, water content, extracellular matrix, and structure of the degenerated NP were significantly improved. MFAT promoted the matrix synthesis function of NPCs, and NPCs stimulated the NP-like differentiation of MFAT cells. In addition, MFAT also partly regenerated degenerated IVDs in the pig model.

The Bone Marrow Niche - The Tumor Microenvironment That Ensures Leukemia Progression

The human body requires a constant delivery of fresh blood cells that are needed to maintain body homeostasis. Hematopoiesis is the process that drives the formation of new blood cells from a single stem cell. This is a complex, orchestrated and tightly regulated process that occurs within the bone marrow. When such process is faulty or deregulated, leukemia arises, develops and thrives by subverting normal hematopoiesis and availing the supplies of this rich milieu.In this book chapter we will describe and characterize the bone marrow microenvironment and its key importance for leukemia expansion. The several components of the bone marrow niche, their interaction with the leukemic cells and the cellular pathways activated within the malignant cells will be emphasized. Finally, novel therapeutic strategies to target this sibling interaction will also be discussed.

Body mass index does not impact hematopoietic progenitor cell mobilization for autologous hematopoietic cell transplantation

BACKGROUND

Obesity has implications for hematopoietic progenitor cell (HPC) mobilization, chemotherapy administration, and medication dosing. We analyzed the impact of obesity on HPC mobilization as well as key outcomes that are associated with cell dose in autologous hematopoietic cell transplantation (AHCT) recipients.

METHODS

We conducted a retrospective cohort study on 556 consecutive eligible AHCT recipients at our institution from 1/2004 to 12/2009. Patients were categorized into four groups based on the body mass index (BMI): underweight (BMI < 18.5), normal (18.5-24.9), overweight (25.0-29.9), or obese (≥30.0). Primary endpoints of interest included HPC mobilization, neutrophil and platelet recovery, hospital stay and survival.

RESULTS

The diagnoses were mostly non-Hodgkin lymphoma, multiple myeloma, and Hodgkin lymphoma. The majority of the patients had received three or less prior chemotherapy regimens and had not received prior radiation therapy. Most patients had chemosensitive disease at time of transplant. For HPC mobilization regimen, 68% received chemotherapy and G-CSF, 32% received G-CSF alone. Busuflan/etoposide/cyclophosphamide, melphalan, and busulfan/cyclophosphamide were used for conditioning. Obesity did not correlate with HPC mobilization and had no association with neutrophil or platelet recovery, or length of transplant hospitalization. On multivariable analysis, obese patients demonstrated better survival than those who were not obese.

CONCLUSION

Obese AHCT recipients had similar rates of HPC mobilization, neutrophil and platelet engraftment and length of transplant hospitalization, and experienced better survival compared with recipients with lower BMI. High BMI by itself should not be considered as a contraindication to AHCT.

Nerve growth factor gene therapy improves bone marrow sensory innervation and nociceptor-mediated stem cell release in a mouse model of type 1 diabetes with limb ischaemia

AIMS/HYPOTHESIS

Sensory neuropathy is common in people with diabetes; neuropathy can also affect the bone marrow of individuals with type 2 diabetes. However, no information exists on the state of bone marrow sensory innervation in type 1 diabetes. Sensory neurons are trophically dependent on nerve growth factor (NGF) for their survival. The aim of this investigation was twofold: (1) to determine if sensory neuropathy affects the bone marrow in a mouse model of type 1 diabetes, with consequences for stem cell liberation after tissue injury; and (2) to verify if a single systemic injection of the NGF gene exerts long-term beneficial effects on these phenomena.

METHODS

A mouse model of type 1 diabetes was generated in CD1 mice by administration of streptozotocin; vehicle was administered to non-diabetic control animals. Diabetic animals were randomised to receive systemic gene therapy with either human NGF or β-galactosidase. After 13 weeks, limb ischaemia was induced in both groups to study the recovery post injury. When the animals were killed, samples of tissue and peripheral blood were taken to assess stem cell mobilisation and homing, levels of substance P and muscle vascularisation. An in vitro cellular model was adopted to verify signalling downstream to human NGF and related neurotrophic or pro-apoptotic effects. Normally distributed variables were compared between groups using the unpaired Student's t test and non-normally distributed variables were assessed by the Wilcoxon-Mann-Whitney test. The Fisher's exact test was employed for categorical variables.

RESULTS

Immunohistochemistry indicated a 3.3-fold reduction in the number of substance P-positive nociceptive fibres in the bone marrow of type 1 diabetic mice (p < 0.001 vs non-diabetic). Moreover, diabetes abrogated the creation of a neurokinin gradient which, in non-diabetic mice, favoured the mobilisation and homing of bone-marrow-derived stem cells expressing the substance P receptor neurokinin 1 receptor (NK1R). Pre-emptive gene therapy with NGF prevented bone marrow denervation, contrasting with the inhibitory effect of diabetes on the mobilisation of NK1R-expressing stem cells, and restored blood flow recovery from limb ischaemia. In vitro hNGF induced neurite outgrowth and exerted anti-apoptotic actions on rat PC12 cells exposed to high glucose via activation of the canonical neurotrophic tyrosine kinase receptor type 1 (TrkA) signalling pathway.

CONCLUSIONS/INTERPRETATION

This study shows, for the first time, the occurrence of sensory neuropathy in the bone marrow of type 1 diabetic mice, which translates into an altered modulation of substance P and depressed release of substance P-responsive stem cells following ischaemia. NGF therapy improves bone marrow sensory innervation, with benefits for healing on the occurrence of peripheral ischaemia. Nociceptors may represent a new target for the treatment of ischaemic complications in diabetes.

Mast Cells and Their Progenitors in Allergic Asthma

Mast cells and their mediators have been implicated in the pathogenesis of asthma and allergy for decades. Allergic asthma is a complex chronic lung disease in which several different immune cells, genetic factors and environmental exposures influence the pathology. Mast cells are key players in the asthmatic response through secretion of a multitude of mediators with pro-inflammatory and airway-constrictive effects. Well-known mast cell mediators, such as histamine and bioactive lipids are responsible for many of the physiological effects observed in the acute phase of allergic reactions. The accumulation of mast cells at particular sites of the allergic lung is likely relevant to the asthma phenotype, severity and progression. Mast cells located in different compartments in the lung and airways have different characteristics and express different mediators. According to in vivo experiments in mice, lung mast cells develop from mast cell progenitors induced by inflammatory stimuli to migrate to the airways. Human mast cell progenitors have been identified in the blood circulation. A high frequency of circulating human mast cell progenitors may reflect ongoing pathological changes in the allergic lung. In allergic asthma, mast cells become activated mainly via IgE-mediated crosslinking of the high affinity receptor for IgE (FcεRI) with allergens. However, mast cells can also be activated by numerous other stimuli e.g. toll-like receptors and MAS-related G protein-coupled receptor X2. In this review, we summarize research with implications on the role and development of mast cells and their progenitors in allergic asthma and cover selected activation pathways and mast cell mediators that have been implicated in the pathogenesis. The review places an emphasis on describing mechanisms identified using in vivo mouse models and data obtained by analysis of clinical samples.