Stromal cell-based immunotherapy in transplantation

Introducing Platelet-Rich Stroma: Platelet-Rich Plasma (PRP) and Stromal Vascular Fraction (SVF) Combined for the Treatment of Androgenetic Alopecia

BACKGROUND

Androgenetic alopecia (AGA) is characterized by miniaturization of the hair follicles gradually causing conversion of terminal hairs into vellus hairs, leading to progressive reduction of the density of hair on the scalp. Approved therapeutic options are limited and show side effects.

OBJECTIVES

To evaluate injections of stromal vascular fraction (SVF), which is rich in adipose-derived stromal cells (ASCs) in combination with platelet-rich plasma (PRP) in the upper scalp as a new autologous treatment option for AGA.

METHODS

Ten male patients (age range, 25-72 years), suffering from AGA at stage II to III according to the Norwood-Hamilton scale, have been treated with a single injection of autologous PRS (ACPSVF: combination of PRP and SVF) in the upper scalp. Preinjection and 6 and 12 weeks postinjection changes in hair density were assessed using ultra high-resolution photography (Fotofinder).

RESULTS

Hair density was significantly increased after 6 weeks and 12 weeks postinjection (P = 0.013 and P < 0.001). In hair-to-hair matching analyses, new hair grew from active follicles. Furhtermore nonfunctioning hair follicles filled with hyperkeartotic plugs, up to today assumed incapable of forming new hair, proved to grow new hair. No side effects were noted after treatment.

CONCLUSIONS

A single treatment of platelet-rich stroma injected in the scalp of patients with AGA significantly increased hair density within 6 to 12 weeks. Further research is required to determine the optimal treatment regimen. Preferred options to our opinion include the repetition of PRS or additional treatments with PRP.

LEVEL OF EVIDENCE 4

Encapsulated Islet Transplantation: Where Do We Stand?

Transplantation of pancreatic islets encapsulated within immuno-protective microcapsules is a strategy that has the potential to overcome graft rejection without the need for toxic immunosuppressive medication. However, despite promising preclinical studies, clinical trials using encapsulated islets have lacked long-term efficacy, and although generally considered clinically safe, have not been encouraging overall. One of the major factors limiting the long-term function of encapsulated islets is the host's immunological reaction to the transplanted graft which is often manifested as pericapsular fibrotic overgrowth (PFO). PFO forms a barrier on the capsule surface that prevents the ingress of oxygen and nutrients leading to islet cell starvation, hypoxia and death. The mechanism of PFO formation is still not elucidated fully and studies using a pig model have tried to understand the host immune response to empty alginate microcapsules. In this review, the varied strategies to overcome or reduce PFO are discussed, including alginate purification, altering microcapsule geometry, modifying alginate chemical composition, co-encapsulation with immunomodulatory cells, administration of pharmacological agents, and alternative transplantation sites. Nanoencapsulation technologies, such as conformal and layer-by-layer coating technologies, as well as nanofiber, thin-film nanoporous devices, and silicone based NanoGland devices are also addressed. Finally, this review outlines recent progress in imaging technologies to track encapsulated cells, as well as promising perspectives concerning the production of insulin-producing cells from stem cells for encapsulation.

Transplantation of Encapsulated Pancreatic Islets as a Treatment for Patients with Type 1 Diabetes Mellitus

Encapsulation of pancreatic islets has been proposed and investigated for over three decades to improve islet transplantation outcomes and to eliminate the side effects of immunosuppressive medications. Of the numerous encapsulation systems developed in the past, microencapsulation have been studied most extensively so far. A wide variety of materials has been tested for microencapsulation in various animal models (including nonhuman primates or NHPs) and some materials were shown to induce immunoprotection to islet grafts without the need for chronic immunosuppression. Despite the initial success of microcapsules in NHP models, the combined use of islet transplantation (allograft) and microencapsulation has not yet been successful in clinical trials. This review consists of three sections: introduction to islet transplantation, transplantation of encapsulated pancreatic islets as a treatment for patients with type 1 diabetes mellitus (T1DM), and present challenges and future perspectives.

Preformed and de novo donor specific antibodies in visceral transplantation: long-term outcome with special reference to the liver

Despite improvement in early outcome, rejection particularly chronic allograft enteropathy continues to be a major barrier to long-term visceral engraftment. The potential role of donor specific antibodies (DSA) was examined in 194 primary adult recipients. All underwent complement-dependent lymphocytotoxic crossmatch (CDC-XM) with pre- and posttransplant solid phase HLA-DSA assay in 156 (80%). Grafts were ABO-identical with random HLA-match. Liver was included in 71 (37%) allografts. Immunosuppression was tacrolimus-based with antilymphocyte recipient pretreatment in 150 (77%). CDC-XM was positive in 55 (28%). HLA-DSA was detectable before transplant in 49 (31%) recipients with 19 continuing to have circulating antibodies. Another 19 (18%) developed de novo DSA. Ninety percent of patients with preformed DSA harbored HLA Class-I whereas 74% of recipients with de novo antibodies had Class-II. Gender, age, ABO blood-type, cold ischemia, splenectomy and allograft type were significant DSA predictors. Preformed DSA significantly (p < 0.05) increased risk of acute rejection. Persistent and de novo HLA-DSA significantly (p < 0.001) increased risk of chronic rejection and associated graft loss. Inclusion of the liver was a significant predictor of better outcome (p = 0.004, HR = 0.347) with significant clearance of preformed antibodies (p = 0.04, OR = 56) and lower induction of de novo DSA (p = 0.07, OR = 24). Innovative multifaceted anti-DSA strategies are required to further improve long-term survival particularly of liver-free allografts.