Effect of Systemic Adipose-derived Stem Cell Therapy on Functional Nerve Regeneration in a Rodent Model.

Regardless of etiology, peripheral nerve injuries (PNI) result in disruption/loss of neuromuscular junctions, target muscle denervation, and poor sensorimotor outcomes with associated pain and disability. Adipose-derived stem cells (ASCs) have shown promise in neuroregeneration. However, there is a paucity of objective assessments reflective of functional neuroregeneration in experimental PNI. Here, we use a multimodal, static, and dynamic approach to evaluate functional outcomes after ASC therapy in a rodent PNI model. METHODS: Lewis rats were divided into 3 groups: 10 mm sciatic nerve resection ("CUT" group; n = 10), transection and repair ("REP" group; n = 10), transection and repair plus single-dose ASCs ("ASC" group; n = 12). Allogeneic (Brown Norway rat) ASCs (1 × 106) were administered intravenously on postoperative day 1. Functional outcome was assessed by static sciatic index, toe spread factor, and a dynamic swim test on a weekly basis for 6 weeks. Sciatic nerves and gastrocnemius muscles were harvested at endpoint (6 weeks) for histological analysis. RESULTS: The ASC group showed accelerated functional recovery on the swim test at 2 weeks postoperatively, with continued improvement over 4 weeks, culminating in superior overall outcomes at 6 weeks compared with the REP group. The CUT group showed no significant improvement from baseline. Nerve histomorphometry correlated well with the swim test results in the ASC group. Gastrocnemius muscle weights showed no difference between the REP and the ASC groups. CONCLUSION: Our study confirms that early, single dose, systemic administration of ASC after PNI accelerates and enhances overall motor recovery on static and dynamic functional tests as evidenced by improvements in voluntary as well as involuntary motions.

Single Implantable FK506 Disk Prevents Rejection in Vascularized Composite Allotransplantation.

BACKGROUND: In vascularized composite allotransplantation, medication nonadherence leads to increased acute rejections. Improving medication adherence would improve overall allograft survival. Regionally delivered immunosuppression, targeted to sites of allorecognition, may reduce or eliminate the need for daily systemic immunosuppression. METHODS: The authors developed biodegradable FK disks containing FK506-loaded double-walled microspheres and tested their efficacy at preventing rejection in a Brown-Norway-to-Lewis rat hindlimb transplantation model. In some experimental group animals, one FK disk was implanted subcutaneously either in native nontransplanted leg or in a transplanted allograft. Regular blood FK506 levels were measured. The endpoint was 180-day allograft survival or grade 3 rejection. At the endpoint, tissue FK506 levels were measured and mixed lymphocytic reaction was performed. RESULTS: A single FK disk maintained systemic blood FK506 levels between 5 and 15 ng/ml for 146 ± 11.1 days. After that, the levels declined to less than 5 ng/ml through the endpoint. There was significantly increased FK506 concentration in groin lymph nodes draining the implanted FK disk. Compared with other groups, animals with an FK disk in the transplanted allograft had 100 percent allograft survival to more than 180 days despite subtherapeutic levels below 5 ng/ml. In these animals, significant T-cell hyporesponsiveness was seen in groin lymph nodes draining the FK disk compared with robust splenic T-cell proliferation. CONCLUSIONS: Sustained regional immunosuppression (with a single FK506 disk) maintained the allograft by means of a high regional concentration of FK506. Notably, this was achieved at subtherapeutic blood concentrations of FK506, without any further systemic FK506 administration.

The Influence of Timing and Frequency of Adipose-Derived Mesenchymal Stem Cell Therapy on Immunomodulation Outcomes After Vascularized Composite Allotransplantation.

BACKGROUND: Cellular therapies for immunomodulation in vascularized composite allotransplantation (VCA) have gained importance due to their potential for minimization of immunosuppression. Adipose-derived (AD) mesenchymal stem cells (MSCs) especially have shown encouraging potential. We investigated the influence of timing and frequency of AD-MSC treatment on immunologic and graft survival as well as graft vasculopathy outcomes after VCA. METHODS: Lewis rats received full-mismatched Brown Norway rat hindlimb transplants. Recipient animals were assigned to groups receiving donor-derived AD-MSCs (10 cells/animal) either on postoperative day (POD) 1, POD 4, or repeatedly on POD 4, 8, and 15, and compared to untreated controls. RESULTS: Although AD-MSC administration on POD 1 or POD 4, 8, and 15 resulted in 50% long-term graft acceptance, recipients treated on POD 4, and controls rejected before POD 50. All treated animals revealed peripheral blood chimerism (4 weeks), most pronounced after repetitive cell administration (12.92% vs 5.03% [POD 1] vs 6.31% [POD 4]; P < 0.05; all P < 0.01 vs control 1.45%). Chimerism was associated with the generation of regulatory T cells (CD4CD25FoxP3). In vitro mixed lymphocyte reactions revealed modulation of the recipient immune response after AD-MSC treatment. Graft arteries at end point revealed significant differences of arterial intimal thickness between rejecting and AD-MSC-treated animals (P < 0.01). CONCLUSIONS: Taken together, our results point to the potential for repetitive AD-MSC administration in improving outcomes after VCA. Future studies are warranted into optimization of the dosing and frequency of AD-MSC therapy, either alone or used in, combination with other cell therapies (such as hematopoietic stem cells or bone marrow-derived MSC or dendritic cells) for optimization of appropriate conditioning or maintenance regimens.

Adipose- and Bone Marrow-Derived Mesenchymal Stem Cells Prolong Graft Survival in Vascularized Composite Allotransplantation.

BACKGROUND: Strategies aiming at minimization or elimination of systemic immunosuppression are key immediate goals for clinical expansion of vascularized composite allotransplantation (VCA). We compared the in vitro and in vivo immunomodulatory efficacy of adipose-derived mesenchymal stem cells (AD-MSCs) and bone marrow (BM)-derived MSCs in a rat VCA model. METHODS: Both cell types were tested in vitro for suppressor function using mixed lymphocyte reactivity assays. AD-MSCs or BM-MSCs were administered intravenously (1 × 10 or 5 × 10 cells/animal) to Lewis rat recipients of mismatched Brown Norway hindlimb transplants. Short course tacrolimus (FK-506) monotherapy was withdrawn at postoperative day 21. In vivo regulatory T-cell induction, peripheral blood chimerism, and microchimerism in lymphatic organs were analyzed. RESULTS: AD-MSCs and BM-MSCs exhibited strong dose-dependent suppressor function in vitro, which was significantly more pronounced for AD cells. In vivo, all animals revealed peripheral multi-lineage chimerism at four weeks (P < 0.01) independent of cell type and dosage. Regulatory T-cell levels were increased with both cell types, the most in AD-MSC groups. These immunomodulatory effects were only transient. MSC treatment resulted in long-term (>120 day) allograft survival in 47% of the animals, which correlated with durable microchimerism in BM and spleen. CONCLUSIONS: AD-MSCs and BM-MSCs exert immunomodulatory effects that prolong survival of immunogenic skin-bearing VCA grafts with short course (21 day) tacrolimus induction therapy. The in vivo findings in terms of allograft survival did not reflect superior immunomodulatory characteristics of AD-MSCs found in vitro.

The role of adipose-derived stem cells in breast cancer progression and metastasis.

Conventional breast cancer extirpation involves resection of parts of or the whole gland, resulting in asymmetry and disfiguration. Given the unsatisfactory aesthetic outcomes, patients often desire postmastectomy reconstructive procedures. Autologous fat grafting has been proposed for reconstructive purposes for decades to restore form and anatomy after mastectomy. Fat has the inherent advantage of being autologous tissue and the most natural-appearing filler, but given its inconsistent engraftment and retention rates, it lacks reliability. Implementation of autologous fat grafts with cellular adjuncts, such as multipotent adipose-derived stem cells (ADSCs), has shown promising results. However, it is pertinent and critical to question whether these cells could promote any residual tumor cells to proliferate, differentiate, or metastasize or even induce de novo carcinogenesis. Thus far, preclinical and clinical study findings are discordant. A trend towards potential promotion of both breast cancer growth and invasion by ADSCs found in basic science studies was indeed not confirmed in clinical trials. Whether experimental findings eventually correlate with or will be predictive of clinical outcomes remains unclear. Herein, we aimed to concisely review current experimental findings on the interaction of mesenchymal stem cells and breast cancer, mainly focusing on ADSCs as a promising tool for regenerative medicine, and discuss the implications in clinical translation.