The application of magnetic nanoparticles (MNPs) in tissue engineering (TE) approaches opens several new research possibilities in this field, enabling a new generation of multifunctional constructs for tissue regeneration. This study describes the development of sophisticated magnetic polymer scaffolds with aligned structural features aimed at applications in tendon tissue engineering (TTE). Tissue engineering magnetic scaffolds are prepared by incorporating iron oxide MNPs into a 3D structure of aligned SPCL (starch and polycaprolactone) fibers fabricated by rapid prototyping (RP) technology. The 3D architecture, composition, and magnetic properties are characterized. Furthermore, the effect of an externally applied magnetic field is investigated on the tenogenic differentiation of adipose stem cells (ASCs) cultured onto the developed magnetic scaffolds, demonstrating that ASCs undergo tenogenic differentiation synthesizing a Tenascin C and Collagen type I rich matrix under magneto-stimulation conditions. Finally, the developed magnetic scaffolds were implanted in an ectopic rat model, evidencing good biocompatibility and integration within the surrounding tissues. Together, these results suggest that the effect of the magnetic aligned scaffolds structure combined with magnetic stimulation has a significant potential to impact the field of tendon tissue engineering toward the development of more efficient regeneration therapies.

Mesenchymal stem cells are multipotent cells, with capacity for self-renewal and differentiation into tissues of mesodermal origin. These cells are possible therapeutic agents for autoimmune disorders, since they present remarkable immunomodulatory ability.The increase of immune-mediated diseases in veterinary medicine has led to a growing interest in the research of these disorders and their medical treatment. Conventional immunomodulatory drug therapy such as glucocorticoids or other novel therapies such as cyclosporine or monoclonal antibodies are associated with numerous side effects that limit its long-term use, leading to the need for developing new therapeutic strategies that can be more effective and safe.The aim of this review is to provide a critical overview about the therapeutic potential of these cells in the treatment of some autoimmune disorders (canine atopic dermatitis, feline chronic gingivostomatitis, inflammatory bowel disease and feline asthma) compared with their conventional treatment.Mesenchymal stem cell-based therapy in autoimmune diseases has been showing that this approach can ameliorate clinical signs or even cause remission in most animals, with the exception of canine atopic dermatitis in which little to no improvement was observed.Although mesenchymal stem cells present a promising future in the treatment of most of these disorders, the variability in the outcomes of some clinical trials has led to the current controversy among authors regarding their efficacy. Mesenchymal stem cell-based therapy is currently requiring a deeper and detailed analysis that allows its standardization and better adaptation to the intended therapeutic results, in order to overcome current limitations in future trials.

Multipotent adipose-derived stromal/stem cells (ASCs) can be isolated with high yield from human subcutaneous lipoaspirates. This study reports our experience isolating, expanding, differentiating and immunophenotypically characterizing ASCs over a period of 4 days after having surgically obtained the lipoaspirate samples. The ultimate goal is to understand how to optimize the consistent isolation of ASCs from lipoaspirates. The length of time between adipose tissue harvest and processing will need to be systematically evaluated with respect to cell yield, viability, and function since some distance is likely to exist between the plastic surgeon’s office where lipoaspiration is performed and the current Good Manufacturing Practices (cGMP) laboratory where the ASCs are isolated. The objective of this study was to determine the effect of time delays on the yield and function of ASCs after collagenase digestion. We were able to isolate ASCs from lipoaspirates up to 72 h after the surgical procedure. The ASCs isolated on sequential days after the original tissue harvest proliferated, differentiated and maintained cell surface markers. We found that the initial 24-hour period is optimal for isolating ASCs with respect to cell yield and that there was no significant difference between ASC cell proliferation and differentiation ability within this period of time. In contrast, each of these parameters declined significantly for tissues maintained at room temperature for 48 or 72 h prior to isolation. These findings should be considered in the future development of standard operating procedures for cGMP processing of clinical-grade human ASCs.

Human adipose-derived stromal/stem cells (ASCs) are an abundant, readily available population of adult stem cells that reside in adipose tissue and that have a great potential utility for tissue engineering and regenerative medicine therapeutic applications. Several preclinical studies have shown that ASCs have therapeutic applicability, but a standardized isolation and expansion methodology for clinical cell therapy has yet to be established. ASC are typically isolated and expanded using reagents with xenogenic components and this may pose certain risks and safety issues, such as exposure to infectious agents and immune reactions, creating further obstacles to the translation of ASC-based therapies to clinical scenarios. The objective of this study was to determine the suitability and efficacy of various alternative enzymatic products, CLS1 (Worthington), CLSAFA (Worthington), NB4 (SERVA), and Liberase (Roche), for the digestion of adipose tissue and subsequent isolation of ASCs, assessing cell functionality concerning their proliferation and differentiation ability. Results show that there are no statistically significant differences on yield and proliferation of cells isolated after enzymatic digestion with any of the studied products. The differentiation potential of the cells was not affected, and cell surface marker expression was similar among all products. We concluded that clinical grade products can replace current research-grade products effectively in our cell isolation protocols without any negative effect in the yield or function of human ASCs.

The repair of large bony defects remains challenging in the clinical setting. Human adipose-derived stromal/stem cells (hASCs) have been reported to differentiate along different cell lineages, including the osteogenic. The objective of the present study was to assess the bone regeneration potential of undifferentiated hASCs loaded in starch-polycaprolactone (SPCL) scaffolds, in a critical-sized nude mice calvarial defect. Human ASCs were isolated from lipoaspirate of five female donors, cryopreserved and pooled together. Critical-sized (4 mm) calvarial defects were created in the parietal bone of adult male nude mice. Defects were either left empty, treated with an SPCL scaffold alone, or SPCL scaffold with human ASCs. Histological analysis and Micro-CT imaging of the retrieved implants were performed. Improved new bone deposition and osseointegration was observed in SPCL loaded with hASC engrafted calvarial defects as compared to control groups that showed little healing. Non differentiated human ASCs enhance ossification of non-healing nude mice calvarial defects, and wet-spun SPCL confirmed its suitability for bone tissue engineering. This study supports the potential translation for ASC use in the treatment of human skeletal defects.

Carrageenans are highly sulphated galactans, well-known for their thermogelation properties which have been extensively exploited in food and cosmetics industry but poorly explored in the biomedicine field. In this study, we have assessed the in vitro and in vivo biocompatibility of κ-carrageenan hydrogels that have been explored for regenerative medicine and tissue engineering applications. The in vitro cytotoxicity of the materials using a L929 mouse fibroblast cell line was evaluated, and the effect of κ-carrageenan hydrogels on the activation of human polymorphonuclear neutrophils cells (hPMNs) was also evaluated by the quantification of reactive oxygen species by chemiluminescence. Subsequently, the inflammatory/immune reaction to κ-carrageenan hydrogels on subcutaneous implantation was studied in rats. Explants were retrieved after 1 and 2 weeks of implantation for histological and RT-PCR analysis. The cytotoxicity screening revealed that κ-carrageenan hydrogels did not significantly affect L929 metabolic activity. Moreover, hPMNs contact with κ-carrageenan resulted in a reduced and a neglectable signal regarding the detection of superoxide and hydroxyl anions, respectively. The results from the in vivo experiments indicated that κ-carrageenan induce a low inflammatory response. Overall, the data obtained suggest that κ-carrageenan hydrogels are biocompatible and thus can be further studied for their use in target biomedical applications.

Namely, in the last two decades, large animal models - small ruminants (sheep and goats), pigs, dogs and horses - have been used to study the physiopathology and to develop new therapeutic procedures to treat human clinical osteoarthritis. For that purpose, cartilage and/or osteochondral defects are generally performed in the stifle joint of selected large animal models at the condylar and trochlear femoral areas where spontaneous regeneration should be excluded. Experimental animal care and protection legislation and guideline documents of the US Food and Drug Administration, the American Society for Testing and Materials and the International Cartilage Repair Society should be followed, and also the specificities of the animal species used for these studies must be taken into account, such as the cartilage thickness of the selected defect localization, the defined cartilage critical size defect and the joint anatomy in view of the post-operative techniques to be performed to evaluate the chondral/osteochondral repair. In particular, in the articular cartilage regeneration and repair studies with animal models, the subchondral bone plate should always be taken into consideration. Pilot studies for chondral and osteochondral bone tissue engineering could apply short observational periods for evaluation of the cartilage regeneration up to 12 weeks post-operatively, but generally a 6- to 12-month follow-up period is used for these types of studies.

Since inflammatory mechanisms have been postulated to link obesity to osteoarthritis, the current study evaluated the ratio of immune cells to multipotent stromal cells within the infrapatellar fat pad (IPFP) and subcutaneous adipose tissue (SQ) of the knee; each depot has potential as a source of regenerative cells. The immunophenotypes of stromal vascular fraction (SVF) and adipose‐derived stem cells (ASCs) of the IPFP and SQ were determined in tissues from osteoarthritic subjects (n = 7) undergoing total knee replacement. Based on a subset of surface antigens, the immunophenotype of ASCs from SQ of OA subjects was not significantly different from that of relatively healthy and leaner subjects undergoing elective liposuction surgery. Flow‐cytometry comparison of SVF cell populations in the IPFP of OA subjects resembled those within the subject's own matched SQ, with the exception of the endothelial marker CD31+, which was significantly greater in cells from SQ. In the OA subjects, lower numbers of capillary‐like structures and higher numbers of stromal and alkaline phosphatase colony‐forming units in the IPFP vs SQ were consistent with this finding; however, ASCs from both depots in OA subjects exhibited comparable adipogenic and osteogenic differentiation potential. Thus, the IPFP contains an ASC and immune cell population similar to that of donor‐matched SQ, making it an alternative ASC source for tissue regeneration. Further studies will be needed to determine whether IPFP immune cell infiltrates play an aetiological role in osteoarthritis equivalent to that shown in diabetes associated with obesity. Copyright © 2012 John Wiley & Sons, Ltd.