Label-free, non-invasive, and repeatable cell viability bioassay using dynamic full-field optical coherence microscopy and supervised machine learning

We present a novel method that can assay cellular viability in real-time using supervised machine learning and intracellular dynamic activity data that is acquired in a label-free, non-invasive, and non-destructive manner. Cell viability can be an indicator for cytology, treatment, and diagnosis of diseases. We applied four supervised machine learning models on the observed data and compared the results with a trypan blue assay. The cell death assay performance by the four supervised models had a balanced accuracy of 93.92 ± 0.86%. Unlike staining techniques, where criteria for determining viability of cells is unclear, cell viability assessment using machine learning could be clearly quantified.

Self-Assembling RADA16-I Peptide Hydrogel Scaffold Loaded with Tamoxifen for Breast Reconstruction

More and more breast cancer patients prefer autologous fat tissue transfer following lumpectomy to maintain perfect female characteristics. However, the outcome was not satisfactory due to the transplanted fat absorption. In this study, we prepared two RADA16-I peptide scaffolds with and without tamoxifen. Both scaffolds were transparent, porous, and hemisphere-shaped. The hADSCs isolated from liposuction were attached to the scaffold. The growth inhibition of the hADSCs induced by TAM in 2-demensional (2D) culture was higher than that in TAM-loaded hydrogel scaffold 3D culture (P < 0.05); however, the same outcomes were not observed in MCF-7 cells. Correspondingly, the apoptosis of the hADSCs induced by TAM was significantly increased in 2D culture compared to that in scaffold 3D culture (P < 0.05). Yet the outcomes of the aoptosis in MCF-7 were contrary. Apoptosis-related protein Bcl-2 was involved in the process. In vivo experiments showed that both scaffolds formed a round mass after subcutaneous implantation and it retained its shape after being pressed slightly. The implantation had no effect on the weight and activity of the animals. The results suggested that TAM-loaded RADA16-I hydrogel scaffolds both provide support for hADSCs cells attachment/proliferation and retain cytotoxic effect on MCF-7 cells, which might be a promising therapeutic breast tissue following lumpectomy.

Introduction of N-cadherin-binding motif to alginate hydrogels for controlled stem cell differentiation

Control of stem cell fate and phenotype using biomimetic synthetic extracellular matrices (ECMs) is an important tissue engineering approach. Many studies have focused on improving cell-matrix interactions. However, proper control of cell-cell interactions using synthetic ECMs could be critical for tissue engineering, especially with undifferentiated stem cells. In this study, alginate hydrogels were modified with a peptide derived from the low-density lipoprotein receptor-related protein 5 (LRP5), which is known to bind to N-cadherin, as a cell-cell interaction motif. In vitro changes in the morphology and differentiation of mouse bone marrow stromal cells (D1 stem cells) cultured in LRP5-alginate hydrogels were investigated. LRP5-alginate gels successfully induced stem cell aggregation and enhanced chondrogenic differentiation of D1 stem cells, compared to RGD-alginate gels, at low cell density. This approach to tailoring synthetic biomimetic ECMs using cell-cell interaction motifs may be critical in tissue engineering approaches using stem cells.

Localization of human adipose-derived stem cells and their effect in repair of diabetic foot ulcers in rats

Background

Diabetic foot ulcer (DFU) is an intractable diabetic complication. Patients suffering from diabetes mellitus (DM) frequently present with infected DFUs. In this study, a wound healing model on diabetic rat foot was established to mimic the pathophysiology of clinical patients who suffer from DFUs. Our study aimed to explore the localization of human adipose-derived stem cells (hADSCs) and the role of these cells in the repair of foot ulcerated tissue in diabetic rats, and thus to estimate the possibilities of adipose-derived stem cells for diabetic wound therapy.

Method

Sprague–Dawley rats were used to establish diabetic models by streptozotocin injection. A full-thickness foot dorsal skin wound was created by a 5 mm skin biopsy punch and a Westcott scissor. These rats were randomly divided into two groups: the hADSC-treated group and the phosphate-buffered saline (PBS) control group. The hADSC or PBS treatment was delivered through the left femoral vein of rats. We evaluated the localization of hADSCs with fluorescence immunohistochemistry and the ulcer area and ulcerative histology were detected dynamically.

Result

The hADSCs had a positive effect on the full-thickness foot dorsal skin wound in diabetic rats with a significantly reduced ulcer area at day 15. More granulation tissue formation, angiogenesis, cellular proliferation, and higher levels of growth factors expression were also detected in wound beds.

Conclusions

Our data suggest that hADSC transplantation has the potential to promote foot wound healing in diabetic rats, and transplantation of exogenous stem cells may be suitable for clinical application in the treatment of DFU.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-016-0412-2) contains supplementary material, which is available to authorized users.

Role of adipose-derived stem cells in wound healing

Impaired wound healing remains a challenge to date and causes debilitating effects with tremendous suffering. Recent advances in tissue engineering approaches in the area of cell therapy have provided promising treatment options to meet the challenges of impaired skin wound healing such as diabetic foot ulcers. Over the last few years, stem cell therapy has emerged as a novel therapeutic approach for various diseases including wound repair and tissue regeneration. Several different types of stem cells have been studied in both preclinical and clinical settings such as bone marrow-derived stem cells, adipose-derived stem cells (ASCs), circulating angiogenic cells (e.g., endothelial progenitor cells), human dermal fibroblasts, and keratinocytes for wound healing. Adipose tissue is an abundant source of mesenchymal stem cells, which have shown an improved outcome in wound healing studies. ASCs are pluripotent stem cells with the ability to differentiate into different lineages and to secrete paracrine factors initiating tissue regeneration process. The abundant supply of fat tissue, ease of isolation, extensive proliferative capacities ex vivo, and their ability to secrete pro-angiogenic growth factors make them an ideal cell type to use in therapies for the treatment of nonhealing wounds. In this review, we look at the pathogenesis of chronic wounds, role of stem cells in wound healing, and more specifically look at the role of ASCs, their mechanism of action and their safety profile in wound repair and tissue regeneration.

GAL3ST2 from mammary gland epithelial cells affects differentiation of 3T3-L1 preadipocytes

INTRODUCTION

In the mammary gland, the involution that occurs when lactation ends is an important period for cancer development. We have previously demonstrated stromal-epithelium interactions evaluating conditioned medium of adipose tissue on breast epithelial metalloproteases activity (Creydt et al., Clin Transl Oncol 15:124-131, 2013). Here, we evaluated the effects of conditioned medium of breast epithelial mammary cells on stromal cells.

MATERIALS AND METHODS

Conditioned medium from normal murine mammary gland cell line (NMuMG) and conditioned medium proteins were obtained. Then, they were evaluated on modulation of adipocyte differentiation, using 3T3-L1 cell line.

RESULTS

We described, for the first time, that breast epithelial mammary cells could produce the enzyme galactose 3-O-sulfotransferase 2 (GAL3ST2). Importantly, GAL3ST2 is present in NMMuMG and two human breast cancer cell lines, and it is more strongly expressed in more metastatic tumors. When 3T3-L1 preadipocyte differentiation was triggered in the presence of conditioned medium from NMuMG or GAL3ST2, triglyceride accumulation was decreased by 40 % and C/EBPβ expression by 80 % in adipocytes. In addition, the expression of FABP4 (aP2), another marker of adipocyte differentiation, was inhibited by 40 % in GAL3ST2-treated cells.

CONCLUSIONS

Taken together, these results suggest that GAL3ST2 would interfere with normal differentiation of 3T3-L1 preadipocytes; raising the possibility that it may affect normal differentiation of stromal preadipocytes and be a link to tumor metastatic capacity.

A quantitative metric for pattern fidelity of bioprinted cocultures

This article describes a quantitative metric for coculture pattern fidelity and its use in the assessment of bioprinting systems. Increasingly, bioprinting is used to create in vitro cell and tissue models for the purpose of studying cell behavior and cell-cell interaction. To create meaningful models, a bioprinting system must be able to place cells in biologically relevant patterns with sufficient fidelity. A metric for assessing fidelity would be valuable for tuning experimental processes and parameters within a bioprinting system and for comparing performance between different systems. Toward this end, the "bioprinting fidelity index" (BFI), a metric which rates a bioprinted patterned coculture with a single number based on the proportions of correctly placed cells, is proposed. Additionally, a mathematical model of drop-on-demand printing is introduced, which predicts an upper bound on the BFI based on drop placement statistics. A proof-of-concept study was conducted in which patterned cocultures of D1 and 4T07 cells were produced in two different demonstration patterns. The BFI for the patterned cocultures was calculated and compared to the printing model fidelity prediction. The printing model successfully predicted the best BFI observed in the samples, and the BFI showed quantitatively that post-processing techniques negatively impacted the final fidelity of the samples. The BFI provides a principled method for comparing printing and post-processing methods.

Same or not the same? Comparison of adipose tissue-derived versus bone marrow-derived mesenchymal stem and stromal cells

Mesenchymal stem/stromal cells (MSCs) comprise a heterogeneous population of cells with multilineage differentiation potential, the ability to modulate oxidative stress, and secrete various cytokines and growth factors that can have immunomodulatory, angiogenic, anti-inflammatory and anti-apoptotic effects. Recent data indicate that these paracrine factors may play a key role in MSC-mediated effects in modulating various acute and chronic pathological conditions. MSCs are found in virtually all organs of the body. Bone marrow-derived MSCs (BM-MSCs) were discovered first, and the bone marrow was considered the main source of MSCs for clinical application. Subsequently, MSCs have been isolated from various other sources with the adipose tissue, serving as one of the alternatives to bone marrow. Adipose tissue-derived MSCs (ASCs) can be more easily isolated; this approach is safer, and also, considerably larger amounts of ASCs can be obtained compared with the bone marrow. ASCs and BM-MSCs share many biological characteristics; however, there are some differences in their immunophenotype, differentiation potential, transcriptome, proteome, and immunomodulatory activity. Some of these differences may represent specific features of BM-MSCs and ASCs, while others are suggestive of the inherent heterogeneity of both BM-MSC and ASC populations. Still other differences may simply be related to different isolation and culture protocols. Most importantly, despite the minor differences between these MSC populations, ASCs seem to be as effective as BM-MSCs in clinical application, and, in some cases, may be better suited than BM-MSCs. In this review, we will examine in detail the ontology, biology, preclinical, and clinical application of BM-MSCs versus ASCs.

Tannic acid cross-linked collagen scaffolds and their anti-cancer potential in a tissue engineered breast implant

Tannic acid (TA) is a hydrolysable plant tannin, and it has been determined that TA functions as a collagen cross-linking agent through hydrogen-bonding mechanisms and hydrophobic effects. Since TA may have anti-tumor properties, it may be a viable cross-linking agent for collagen-based breast tissue scaffolds. The goal of this work was to determine if TA cross-linked scaffolds induce apoptotic processes in MCF-7 cancer cells, with minimal toxic effect on healthy D1 mesenchymal stem-like stromal cells. Cross-linked collagen scaffolds that were uniform, easily reproduced, easily characterized, and readily used in cell culture were manufactured. Thermal denaturation temperatures of the cross-linked scaffolds (68°C) were shown to be significantly higher when compared to those of uncross-linked scaffolds (55°C). Scanning electron microscopy images demonstrated the replacement of irregular collagen fibers with sheet-like structures upon cross-linking. The cross-linking solution concentration of TA that appears to be best for inducing apoptotic processes in MCF-7 cells, while minimizing toxic effect on D1 cells, is 1 mg/ml. At this concentration, the MCF-7 cell metabolic activity did not change over a 72-h period (i.e., proliferation was limited) while there was an increase in metabolic activity of D1 cells over the 72-h period. TA did appear to inhibit the production of lipid by D1 cells cultured in an adipogenic cocktail; in the future, the rate and duration of inhibition could be tailored to allow gradual bulking of the implant. The results suggest that the level of TA cross-linking can be modulated to provide optimal use in a tissue engineering composite.

Clinical and preclinical translation of cell-based therapies using adipose tissue-derived cells

Adipose tissue is now recognized as an accessible, abundant, and reliable site for the isolation of adult stem cells suitable for tissue engineering and regenerative medicine applications. The past decade has witnessed an explosion of preclinical data relating to the isolation, characterization, cryopreservation, differentiation, and transplantation of freshly isolated stromal vascular fraction cells and adherent, culture-expanded, adipose-derived stromal/stem cells in vitro and in animal models. This body of work has provided evidence supporting clinical translational applications of adipose-derived cells in safety and efficacy trials. The present article reviews the case reports and phase I-III clinical evidence using autologous adipose-derived cells that have been published, to date, in the fields of gastroenterology, neurology, orthopedics, reconstructive surgery, and related clinical disciplines. Future directions and challenges facing the field are discussed and evaluated.

Building off-the-shelf tissue-engineered composites

Rapid advances in technology have created the realistic possibility of personalized medicine. In 2000, Time magazine listed tissue engineering as one of the 'hottest 10 career choices'. However, in the past decade, only a handful of tissue-engineered products were translated to the clinical market and none were financially viable. The reality of complex business planning and the high-investment, high-technology environment was not apparent, and the promise of tissue engineering was overstated. In the meantime, biologists were steadily applying three-dimensional benchtop tissue-culture systems for cellular research, but the systems were gelatinous and thus limited in their ability to facilitate the development of complex tissues. Now, the bioengineering literature has seen an emergence of literature describing biofabrication of tissues and organs. However, if one looks closely, again, the viable products appear distant. 'Rapid' prototyping to reproduce the intricate patterns of whole organs using large volumes of cellular components faces daunting challenges. Homogenous forms are being labelled 'tissues', but, in fact, do not represent the heterogeneous structure of the native biological system. In 2003, we disclosed the concept of combining rapid prototyping techniques with tissue engineering technologies to facilitate precision development of heterogeneous complex tissue-test systems, i.e. systems to be used for drug discovery and the study of cellular behaviour, biomedical devices and progression of disease. The focus of this paper is on the challenges we have faced since that time, moving this concept towards reality, using the case of breast tissue as an example.