InTechOpen uses cookies to offer you the best online experience. By continuing to use our site, you agree to our Privacy Policy.

Medicine » Gastroenterology » "New Insights into Inflammatory Bowel Disease", book edited by Samuel Huber, ISBN 978-953-51-2755-0, Print ISBN 978-953-51-2754-3, Published: October 26, 2016 under CC BY 3.0 license. © The Author(s).

Chapter 12

Autologous and Allogeneic Stem Cell Transplantation for Treatment of Crohn’s Fistulae

By Fernando de la Portilla, Ana M. García‐Cabrera, Rosa M. Rodríguez‐ Jiménez, Maria L. Reyes and Damian García‐Olmo
DOI: 10.5772/64546

Article top

Autologous and Allogeneic Stem Cell Transplantation for Treatment of Crohn’s Fistulae

Fernando de la Portilla1, Ana M. García‐Cabrera1, Rosa M. Jiménez‐Rodríguez1, Maria L. Reyes1 and Damian García‐Olmo2
Show details


Up to 20% of patients with Crohn’s disease (CD) may have perianal fistula disease. Classically, surgery has played an important role; in recent years, medical treatment has taken a leading role. Immunosuppressants and biological trea tments have proven beneficial in many patients, but still, the percentage of patients who do not respond remains significant. In this scenario, cell therapy is envisaged as an effective alternative to surgery. The promising preclinical and clinical data that we review below suggest that cell therapy could represent a major advance in the clinical management of this difficult problem.

Keywords: stem cells, allogenic, autologous, transplantation, Crohn, fistulas

1. Introduction

Up to 20% of patients with Crohn’s disease (CD) may have perianal fistula disease, which is frequently associated with perianal collections [13]. Classically, surgery has played an important role, by the placement of drains or setons creation of ostomies, and in severe cases, even proctectomy [4]. However, in recent years, medical treatment with or without the temporary placement of drains has taken a leading role. Immunosuppressants such as azathioprine, 6‐mercaptopurine, methotrexate and cyclosporine have proven beneficial in many patients. In more complicated cases where these drugs are ineffective, biological treatments based on monoclonal antibodies have been shown to have some success for the induction and maintenance of remission of perianal fistula disease and associated proctitis [511]. Still, the percentage of patients who do not respond or do so only partially remains significant. Furthermore, the existence of serious complications associated with treatment should not be overlooked [9, 12, 13].

It is as a result of these inadequacies in current treatment strategies that cell therapy has arisen as a complementary option [14]. The promising results published in recent years, both with autologous and in allogeneic cells, highlight a need for greater understanding of the basic principles of this new route and for clarification of the current state of the topic.

2. Basic concepts of cell therapy

Stem cells have both the capacity for self‐renewal or self‐replication and for production of daughter cells that proceed along specific developmental pathways that will eventually lead to differentiation into specialised cell types [15].

Embryonic stem cells are obtained from the inner cell mass of the embryo at the blastocyst stage. They are able to generate cell lines derived from any of the three embryonic germ layers (ectoderm, mesoderm and endoderm), giving them great therapeutic potential. In mature adult tissues, we find adult multipotent stem cells, which are generally only able to renew and regenerate tissues from the embryonic layer of which they come. However, based on the so‐called phenomenon of cellular plasticity, in some instances, they can differentiate into cell populations different to those of their embryonic origin, providing many therapeutic options [16].

Finally, we have the so‐called induced pluripotent stem cells (iPS), which are somatic cells that have been subjected to a process of nuclear reprogramming by ectopic expression of specific transcription factors. These acquire molecular and functional characteristics of pluripotency that make them akin to embryonic stem cells. They also display similar characteristics to these in terms of morphology, proliferation, gene expression, epigenetic status of pluripotent genes and their ability to differentiate in vivo and in vitro [17].

Although embryonic stem cells and iPS have great potential for cell‐based therapies, there are several limitations to their use, including regulatory, ethical and genetic engineering considerations. As a result, there are currently no clinical trials evaluating their use [18].

On the other hand, adult stem cells can be obtained using much simpler methods and have no restrictions or ethical considerations. Furthermore, because of their autologous origin, they are not immunoreactive. Early studies using adult stem cells have focused on mesenchymal stem cells (MSCs). These can be found in the stroma of virtually every organ, for example, in subcutaneous adipose tissue and bone marrow. Being fibroblastoid cells, they are the precursors of all types of non‐haematopoietic connective tissues (bone, fat, cartilage, etc.). MSCs are generally obtained by selection through adherence to tissue culture plastic, as they are able to adhere and grow in conditions where other cell types do not usually proliferate [19]. They are required to meet minimal criteria defined by the International Society for Cellular Therapy, namely, more than 95% of cells must express CD105, CD73 and CD90, as measured by flow cytometry; and <2% must be positive for CD45, CD34, CD14, CD11b, CD79a or CD19 and human leukocyte antigen (HLA) Class II. Moreover, they should be able to differentiate into osteoblasts, chondroblasts and adipocytes under standard in vitro differentiation conditions [20].

MSCs have a high capacity for proliferation and differentiation. Furthermore, under certain experimental conditions, they have displayed the ability to differentiate into non‐connective cell lineages, such as neuronal and endothelial. Finally, as a particularly interesting property for the use at hand, they are capable, both in vitro and in vivo, of inhibiting immune response. This ability to immunoregulate includes inhibition of the activation of T, B and NKcells, the maturation of dendritic cells, as well as protecting against inflammatory and/or autoimmune pathologies, including transplant rejection [21].

3. Mesenchymal stem cells as therapies

Early studies with adult stem cells focused on MSCs isolated from bone marrow stroma, which have demonstrated adipogenic, osteogenic, chondrogenic, myogenic and neurogenic potential in vitro. However, obtaining stem cells from this source is painful for the patient and only provides a small number of cells [22]. Recently, methods of harvesting adult stem cells from adipose tissue by simple liposuction have been developed. Adipose tissue is rich in such cells, and their preparation is easier than that from bone marrow. Although there is some debate about whether stem cells originate in the fat tissue itself, or if perhaps they are mesenchymal or even peripheral blood stem cells passing through the fat, it is clear that adipose tissue represents a valuable source of potentially useful stem cells. These adipose‐derived stem cells (ASCs) have been shown to have an inherent ability to self‐renew, proliferate and differentiate into mature tissues, depending on the microenvironment that surrounds them. Such characteristics, intrinsic to all stem cells, make them highly attractive for use in cell therapy and regenerative medicine [23].

Interest in multipotent ASCs is increasing, owing to the ability to harvest large quantities of tissue under local anaesthesia via the liposuction process. Indeed, from just 1 g of adipose tissue, 5 × 103 stem cells can be obtained, which is much greater than the amount that can be acquired from bone marrow. Furthermore, compared to bone marrow MSCs, in the early stages, ASCs express CD34 to a greater extent (100–500 times higher) [24].

The terms adipose tissue‐derived stromal cell (ADSC), adipose stromal–vascular cell fraction (SVF) and adipose‐derived regenerative cells (ADRC) all correspond to cells obtained immediately after digestion of adipose tissue by collagenase. On the other hand, the terms processed lipoaspirate cells (PLA) and plastic‐adherent adipose‐derived stem cells (ASCS) describe those that are obtained after culturing those produced by the digestion process. As a unifying term, we refer to these cell types as adipose‐derived stem cells (ASC), in accordance with the International Fat Applied Technology Society Consensus [25].

4. Utilisation of MSCs in the treatment of perianal fistula disease

The precise mechanism of the therapeutic action of MSCs is not fully understood, but is likely to reflect their inherent characteristics, in particular their differentiation potential [26, 27]. MSCs have the ability to migrate to the site of a lesion or inflammatory process, stimulate the proliferation and differentiation of resident stem cells through the secretion of growth factors, remodel the matrix and exert an immunomodulatory and anti‐inflammatory effect. Together, these properties aid help the healing of tissues [2831]. It has also been demonstrated that MSCs can induce an increase in epithelialisation and angiogenesis through a process of differentiation and paracrine interaction with skin cells [3234].

Today, we know that Crohn’s disease delays T‐cell apoptosis [35, 36], and a mechanism of action of ASCs when injected into the inflammation site in the fistula tract has been postulated. Initially, the cells recognise proinflammatory cytokines such as IFN‐γ, followed by activation of the indoleamine 2,3‐dioxygenase (IDO) enzyme, which is ultimately responsible for creating a microenvironment—lymphocyte freezing by inhibition of phosphorylation. This results in a reduction in the release of proinflammatory mediators (TNF‐α, IL‐6, etc.) and an increase in that of anti‐inflammatory species such as IL‐10 [37].

5. Treatment protocol for anal fistulae

The protocol for stem cell treatment of anal fistulae inevitably starts with the harvesting of the MSCs, either from the patient’s bone marrow or their fat (autologous), or from a healthy donor (allogeneic). Bone marrow cells are harvested by aspiration, and then, the MSCs are expanded ex vivo for subsequent use in the fistula tract [38, 39]. Although there are various protocols for expansion and differentiation of cells obtained from adipose tissue (with a consequent variation in results), ASCs are normally used after digestion with collagenase under constant stirring. The obtained solution is then centrifuged at low speed, and the resultant is filtered through a nylon mesh of 40–200 μm. The new solution is then centrifuged again, and the cells are re‐suspended in fresh expansion medium. It is important to stress that this procedure must be carried out in extremely sterile conditions [40].

As for the route of administration, there is a single study in which allogeneic bone marrow MSCs were given intravenously, with the closure of fistulas being a secondary objective of the study [41]; all other published studies have employed the intralesional route [38, 39, 4250].

Before intralesional injection of the isolated MSCs, the lesion site must be prepared with similarly intensive curettage, avoiding the use of cytolytic substances (hydrogen peroxide). The inner fistula orifice can then be sealed with an absorbable suture. At this point, half of the cell preparation is administered to the tissue around the inner hole, making small submucosal wheals. The other half is applied along the walls of the fistula tract, if possible along its whole length, while taking care not to go deeper than a few millimetres, again in small wheals (Figure 1). Several studies have investigated the use of fibrin glue as an adjuvant or scaffold, in order to enhance the attachment of cells in the fistula tract [43, 4547]. The dose of cells required for optimum results remains to be determined; in published studies, this ranges from 3.5 × 106 to 40 × 106 cells [3950].


Figure 1.

Implant points. (a) Wheal in the internal fistula orifice; (b) injection in the fistula tract at a depth of no more than 2 mm (courtesy of Tigenix).

Most studies have used ASCs, but there are also some that have evaluated the use of bone marrow cells. As for the cell source, the advantages of an allogeneic source (from healthy donors) are innumerable in comparison with those of an autologous source, especially in terms of greater accessibility, easy expandability and good stability. Their use is possible because of their low immunogenicity and limited persistence, which reduce the chances of provoking an adverse effect in the host [51].

6. Safety and efficacy of MSCs in the treatment of anal fistulae

The first experience with stem cells in the treatment of anal fistulae was reported by García‐Olmo et al. [52]. Several studies have since been published, the majority of which are from Spanish groups. The MSCs used have mainly originated from adipose tissue, with only two studies using bone marrow MSCs. In these latter cases, both allogeneic and autologous cells have been used. In all studies, administration was intralesional, with fibrin glue often used [38, 39].

Today, any questions as to the feasibility and safety of such treatment seem to have been resolved, at least within the range of doses used. A retrospective study evaluating whether MSC treatment has any influence on fertility, course of pregnancy, birthweight or physical status was recently published [53]. Five patients with fistula associated with Crohn’s disease treated with ASCs, and who indicated their intention to have children after completion of treatment, were tracked. Fertility and pregnancy course were not found to be affected by this therapy. Furthermore, no treatment‐related malformations in newborns were observed. Therefore, it was concluded that in the patients analysed in the study, local injection of ASCs was not associated with adverse effects on the ability to conceive, pregnancy course or the newborn’s condition.

In the published literature, there are differences in cure rate depending on the follow‐up, but in general, it is estimated to be between 50 and 70% (Table 1).

Authors, yearStudy designSource of cellsResults
Garcia‐Olmo et al., 2005 (Spain) [42]Phase I clinical study (n = 4)ASCs (autologous)Complete closure: 50% of patients; 75% fistulas
Garcia‐Olmo et al., 2009 (Spain) [42]Open‐label, multicenter, phase II study (n = 14)ASCs (autologous); fibrin glueFistula healing: 71 vs 14%
Ciccocioppo et al., 2011 (Italy) [38]Prospective study (n = 10)MSCs (autologous)Reduction in CDAI, PDAI and pain/discharge PDAI scores
Guadalajara et al., 2012 (Spain) [43]Retrospective follow‐up of Garcia‐Olmophase II study (n = 5)ASCs (autologous); fibrin glue58% sustained fistula closure at end of follow‐up by mean
3 years No safety problem
Cho et al., 2013
(Korea) [47]
Open‐label, multicentre, dose escalationphase I study (n = 10)ASCs (autologous); fibrin glueHealing in 50% in the group with 2 × 107 cells
Lee et al., 2013
(Korea) [45]
Open‐label, multicentre, phase II study (n = 42; 33 completed
ASCs (autologous); fibrin glueFistula closure in 79%, recidive 11%
de la Portilla et al., 2013 (Spain) [48]Open‐label pilot study (n = 24)ASCs (allogeneic)Complete closure: 56.3% at 24 weeks
Ciccocioppo et al., 2015 (Italy) [44]5‐year follow‐up of 2011 study
(n = 10)
MSCs (autologous)37% fistula relapse‐free 4 years later
Cho et al., 2013
(Korea) [46]
Retrospective, 1‐year follow‐up from 2013 studyASCs (autologous); fibrin glueComplete closure maintained in 75% at 2 years ITT analysis; 80% PP analysis
Garcia‐Olmo et al., 2015 (Spain) [49]Retrospective, open‐label
(n = 3 with CD)
ASCs (allogeneic andautologous)Healing in 2/3 CD fistula patients
Molendijk et al., 2015
(The Netherlands) [39]
Double‐blind, placebo‐controlledphase II study (n = 21)MSCs (allogeneic)Healing up to 85%
Park et al., 2015
(Korea) [50]
Multicentre, open‐label, dose escalation pilot study (n = 6)ASCs (allogeneic); fibrin glueGroup 1 (1 × 107 cells/ml); healing 100% Group 2 (3 × 107 cells/ml); healing 100%

Table 1.

Published studies using MSCs to treat Crohn’s disease patients with perianal fistulas.

[i] - ASCs, adipose‐derived stem cells; CD, Crohn’s disease; CDAI, Crohn’s disease activity index; ITT, intention to treat; IV, intravenous; MSCs, mesenchymal stem cells/mesenchymal stromal cells; PDAI, Pouchitis disease activity index; PP, per protocol; SC, stem cells.

Ciccocioppo et al. evaluated the long‐term safety and efficacy of the use of bone‐marrow‐derived MSCs. In their study, 8 patients were followed prospectively for 72 months. These patients were part of a phase I/II trial previously conducted, in which a cure rate of 70% per year was reported, with improvement observed in the remaining 30% [44]. Patients received serialised injections of MSCs (4 on average) at intervals of 4 weeks. Secondary endpoints were the time patients remained without fistula and the time they were free of medical or surgical treatment. The Chrohn’s Disease Activity Index (CDAI) increased over the first 2 years, followed by a gradual decline in the third year, and stabilisation at the end of follow‐up at figures similar to those of the first year. The probability of remaining without fistula was 88% for the first year, 50% at 2 years and 37% over the next 4 years. The probability of patients being free from surgery was 100% for the first year, 75% for years 2–4 and 63% at years 5 and 6. Finally, the probability of patients being free from medical treatment was 88% for the first year, 25% at years 2–4 and 25% at years 5 and 6. No adverse effects related to treatment in these follow‐up periods were recorded. The authors conclude that the fact that the activity indices increase again in the second year might suggest that this therapy is not curative, but that it does improve the remission rate in patients with refractory disease. Moreover, almost all patients required the reintroduction of biological or immunosuppressive therapy after the second year [44].

We are currently awaiting the publication of the results of a phase III, randomised, placebo, double‐blind, multicentre, and international clinical trial employing Cx601, a preparation of allogeneic ASCs. It has recently been reported that, after 24 weeks, Cx601 was statistically superior to placebo in achieving the combined response (clinical and imaging) of complex perianal fistulas in Crohn’s disease patients whose response to previous treatment, including anti‐TNFs, had been inadequate.

7. Future perspectives

There is no doubt that a new avenue has opened for the treatment of Crohn’s disease patients suffering from fistulae refractory to conventional therapy. Since the first description of the treatment, interest in this therapy has grown, so that in addition to the 11 studies published to date, at the time we write this chapter, there are more than a dozen clinical trials in recruitment or in the results publication phase.

While the safety of ASC therapy seems to have been well established, the optimal dosage, route of administration (intravenous versus intralesional), administration technique (alone or together with fibrin glue), among other matters, are yet to be adequately determined. However, these should be investigated and resolved in the coming years.


Tigenix SAU thank for the help in the writing of this chapter and easy editing of figures and particularly Dra. Mary Carmen Díaz


1 - Schwartz DA, Loftus EV, Tremaine WJ. The natural history of fistulizing Crohn’s disease in Olmsted Country, Minnesota. Gastroenterology. 2002;122:875–880. doi:10.1053/gast.2002.32362
2 - Ardizzone S, Bianchi‐Porro G. Perianal Crohn’s disease: overview. Dig Liver Dis. 2007;39:957–958. doi:10.1016/j.dld.2007.07.152
3 - Ingle SB, Loftus EV. The natural history of perianal Crohn’s disease. Dig Liver Dis. 2007;39:963–969. doi:10.1016/j.dld.2007.07.154
4 - Singh B, George BD, Mortensen NJ. Surgical therapy of perianal Crohn’s disease. Dig Liver Dis. 2007;39:988–992. doi:10.1016/j.dld.2007.07.157
5 - Sandborn WJ, Fazio VW, Feagan BG. AGA technical review on perianal Crohn’s disease. Gastroenterology. 2003;125:1508–1530. doi:10.1016/j.gastro.2003.08.025
6 - Griggs L, Schwartz DA. Medical options for treating perianal Crohn’s disease. Dig Liver Dis. 2007;39:979–987. doi:10.1016/j.dld.2007.07.156
7 - Present DH, Rutgeerts P, Targan S. Infliximab for the treatment of fistulas in patients with Crohn’s disease. N Engl J Med. 1999;340:1398–1405. doi:10.1056/NEJM199905063401804
8 - Sands BE, Anderson FH, Bernstein CN. Infliximab maintenance therapy for fistulizing Crohn’s disease. N Engl J Med. 2004;350:876–885. doi:10.1056/NEJMoa030815
9 - Rutgeerts P, Feagan BG, Lichtenstein GR. Comparison of scheduled and episodic treatment strategies of infliximab in Crohn’s disease. Gastroenterology.2004;126:402–413. doi:10.1053/j.gastro.2003.11.014
10 - Van der Hagen SJ, Baeten CG, Soeters PB. Anti‐TNFalpha (infliximab) used as induction treatment of active proctitis in a multistep strategy followed by definitive surgery of complex anal fistulas in Crohn’s disease: a preliminary report. Dis Colon Rectum. 2005;48:758–767. doi:10.1007/s10350‐004‐0828‐0
11 - Schroder O, Blumenstein I, Schulte‐Bockholt A. Combining infliximab and methotrexate in fistulizing Crohn’s disease resistant or intolerant to azathioprine. Aliment Pharmacol Ther. 2004;19:295–301. doi:10.1111/j.1365‐2036.2004.01850.x
12 - Ochsenkuhn T, Goke B, Sackmann M. Combining infliximab with 6‐mercaptopurine/azathioprine for fistula therapy in Crohn’s disease. Am J Gastroenterol. 2002;97:2022–2025. doi:10.1111/j.1572‐0241.2002.05918.x
13 - Baert F, Noman M, Vermeire S. Influence of immunogenicity on the long‐term efficacy of infliximab in Crohn’s disease. N Engl J Med. 2003;348:601–608. doi:10.1056/NEJMoa020888
14 - García‐Olmo D, García‐Arranz M, Herreros D, Pascual I, Peiro C, Rodríguez‐Montes JA. A phase I clinical trial of the treatment of Crohn’s fistula by adipose mesenchymal stem cell transplantation. Dis Colon Rectum. 2005;48:1416–1423. doi:10.1007/s10350‐005‐0052‐6
15 - Gardner RL. Stem cells and regenerative medicine: principles, prospects and problems. C R Biol. 2007;330:465–473. doi:10.1016/j.crvi.2007.01.005
16 - Marshak DR, Gardner RL, Gottlieb D. Stem cell biology. New York: Cold Spring Harbor Laboratory Press; 2001. 550 p. doi:10‐87969‐575‐7/01
17 - Yamanaka S. Pluripotency and nuclear reprogramming. Phil Trans R Soc Lond B Biol Sci. 2008;363:2079–2087. doi:10.1098/rstb.2008.2261
18 - Trebol Lopez J, Georgiev Hristov T, García‐Arranz M, García‐Olmo D. Stem cell therapy for digestive tract diseases: current state and future perspectives. Stem Cells Dev. 2011;20:1113–1129. doi:10.1089/scd.2010.0277
19 - Verfaillie CM. Adult stem cells: assessing the case for pluripotency. Trends Cell Biol. 2002;12:502–508.doi:10.1016/S0962‐8924(02)02386‐3
20 - Chamberlain G, Fox J, Ashton B, Middleton J. Concise review: mesenchymal stem cells: their phenotype, differentiation capacity, immunological features, and potential for homing. Stem Cells. 2007;25:2739–2749.doi:10.1634/stemcells.2007‐0197
21 - García‐Gómez I, Elvira G, Zapata AG, et al. Mesenchymal stem cells: biological properties and clinical applications. Expert Opin Biol Ther. 2010;10(10):1453–1468. doi:10.1517/14712598.2010.519333
22 - Singer AJ, Clark RAF. Cutaneous wound healing. N Engl J Med. 1999;341:738–746. doi:10.1056/NEJM199909023411006
23 - Stappenbeck TS, Miyoshi H. The role of stromal stem cells in tissue regeneration and wound repair. Science. 2009;324:1666–1669.doi:10.1126/science.1172687
24 - Keating A. Mesenchymal stromal cells. Curr Opin Hematol. 2006;13:419–425. doi:10.1097/01.moh.0000245697.54887.6f
25 - Dominici M, Le Blanc K, Mueller I, et al. Minimal critering for definig multipotent mesenchymal stromal cells. The International Society for Cellular Therapy position statement. Cytotherapy. 2006;83:15. doi:10.1080/14653240600855905
26 - Gimble JM, Guilak, F. Adipose‐derived adult stem cells: isolation, characterization, and differentiation potential. Cytotherapy.2003;5:362–369. doi:10.1080/14653240310003026
27 - Gimble, JM, Katz AJ, Bunnell BA. Adipose‐derived stem cells for regenerative medicine. Circ Res.2007;100:1249–1260. doi:10.1161/01.RES.0000265074.83288.09
28 - Chapel A, Bertho JM, Bensidhoum M, et al. Mesenchymal stem cells home to injured tissues when co‐infused with hematopoietic cells to treat a radiation‐induced multi‐organ failure syndrome. J Gene Med. 2003;5:1028–1038. doi:10.1002/jgm.452
29 - Le Blanc, K. Mesenchymal stromal cells: tissue repair and immune modulation. Cytotherapy.2006;8:559–561. doi:10.1080/14653240601045399
30 - Yagi H, Soto‐Gutierrez A, Parekkadan B, et al. Mesenchymal stem cells: mechanisms of immunomodulation and homing. Cell Transplant. 2010;19:667–679. doi:10.3727/096368910X508762
31 - Yoo KH, Jang IK, Lee MW, et al. Comparison of immunomodulatory properties of mesenchymal stem cells derived from adult human tissues. Cell Immunol. 2009;259:150–156. doi:10.1016/j.cellimm.2009.06.010
32 - Falanga V, Iwamoto S, Chartier M, et al. Autologous bone marrow derived cultured mesenchymal stem cells delivered in a fibrin spray accelerate healing in murine and human cutaneous wounds. Tissue Eng. 2007;13:1299–1312. doi:10.1038/jid.2012.77
33 - McFarlin K, Gao X, Liu YB, et al. Bone marrow‐ derived mesenchymal stromal cells accelerate wound healing in the rat. Wound Repair Regen. 2006;14:471–478. doi:10.1111/j.1743‐6109.2006.00153.x
34 - Wu Y, Chen L, Scott PG, et al. Mesenchymal stem cells enhance wound healing through differentiation and angiogenesis. Stem Cells. 2007;25:2648–2659. doi:10.1634/stemcells.2007‐0226
35 - Ina K, Itoh J, Fukushima K, et al. Resistance of Crohn’s disease T cells to multiple apoptotic signals is associated with a Bcl‐2/Bax mucosal imbalance. J Immunol. 1999;163:1081–1090. doi:10.0022‐1767/99/02.00
36 - Mudter J, Neurath MF. Apoptosis of T cells and the control of inflammatory bowel disease: therapeutic implications. Gut. 2007;56:293–303.doi:10.1136/gut.2005.090464
37 - De la Rosa O, Lombardo E, Beraza A, et al. Requirement of IFN‐gamma‐mediated indoleamine 2,3‐dioxygenase expression in the modulation of lymphocyte proliferation by human adipose‐derived stem cells. Tissue Eng Part A. 2009;15:2795–2806. doi:10.1089/ten.TEA.2008.0630
38 - Ciccocioppo R, Bernardo ME, Sgarella A, Maccario R, Avanzini MA, Ubezio C, Minelli A, Alvisi C, Vanoli A, Calliada F, Dionigi P, Perotti C, Locatelli F, Corazza GR. Autologous bone marrow derived mesenchymal stromal cells in the treatment of fistulising Crohn’s disease. Gut. 2011;60:788–798. doi:10.1136/gut.2010.214841
39 - Molendijk I, Bonsing BA, Roelofs H, Peeters KC, Wasser MN, Dijkstra G, van der Woude CJ, Duijvestein M, Veenendaal RA, Zwaginga JJ, Verspaget HW, Fibbe WE, van der Meulen‐de Jong AE, Hommes DW. Allogeneic bone marrow‐derived mesenchymal stromal cells promote healing of refractory perianal fistulas in patients with Crohn’s disease. Gastroenterology. 2015;149(4):918–927.e6. doi:10.1053/j.gastro.2015.06.014
40 - Casteilla L, Planat‐Benard V, Bourin P, Laharrague P, Cousin B. Use of adipose tissue in regenerative medicine. Transfus Clin Biol. 2011;18:124–128. doi:10.1016/j.tracli.2011.01.008
41 - Mannon PJ. Remestemcel‐L: human mesenchymal stem cells as an emerging therapy for Crohn’s disease. Expert Opin Biol Ther.2011;11:1249–1256. doi:10.1517/14712598.2011.602967
42 - Garcia‐Olmo D, Herreros D, Pascual I, Pascual JA, Del‐Valle E, Zorrilla J, De‐La‐Quintana P, Garcia‐Arranz M, Pascual M. Expanded adipose‐derived stem cells for the treatment of complex perianal fistula: a phase II clinical trial. Dis Colon Rectum. 2009;52:79–86. doi:10.1007/DCR.0b013e3181973487
43 - Guadalajara H, Herreros D, De‐La‐Quintana P, Trebol J, Garcia‐Arranz M, Garcia‐Olmo D. Long‐term follow‐up of patients undergoing adipose derived adult stem cell administration to treat complex perianal fistulas. Int J Colorectal Dis. 2012;27:595–600. doi:10.1007/s00384‐011‐1350‐1
44 - Ciccocioppo R, Gallia A, Sgarella A, Kruzliak P, Gobbi PG, Corazza GR. Long‐term follow‐up of Crohn disease fistulas after local injections of bone marrow‐derived mesenchymal stem cells. Mayo Clin Proc. 2015;90:747–755. doi:10.1016/j.mayocp.2015.03.023
45 - Lee WY, Park KJ, Cho YB, Yoon SN, Song KH, Kim do S, Jung SH, Kim M, Yoo HW, Kim I, Ha H, Yu CS. Autologous adipose tissue‐derived stem cells treatment demonstrated favorable and sustainable therapeutic effect for Crohn’s fistula. Stem Cells. 2013;31:2575–2581. doi:10.1002/stem.1357
46 - Cho YB, Lee WY, Park KJ, Kim M, Yoo HW, Yu CS. Autologous adipose tissue‐derived stem cells for the treatment of Crohn’s fistula: a phase I clinical study. Cell Transplant. 2013;22:279–285. doi:10.3727/096368912X656045
47 - Cho YB, Park KJ, Yoon SN, Song KH, Kim do S, Jung SH, Kim M, Jeong HY, Yu CS. Long‐term results of adipose‐derived stem cell therapy for the treatment of Crohn’s fistula. Stem Cells Transl Med. 2015;4:532–537. doi:10.5966/sctm.2014‐0199
48 - de la Portilla F, Alba F, García‐Olmo D, Herrerías JM, González FX, Galindo A. Expanded allogeneic adipose‐derived stem cells (eASCs) for the treatment of complex perianal fistula in Crohn’s disease: results from a multicenter phase I/IIa clinical trial. Int J Colorectal Dis. 2013;28:313–323. doi:10.1007/s00384‐012‐1581‐9
49 - Garcia-Olmo D, Guadalajara H, Rubio-Perez I, Herreros MD, de-la-Quintana P,Garcia-Arranz M. Recurrent anal fistulae: limited surgery supported by stem cells. World J Gastroenterol. 2015 Mar 21;21(11):3330–6. doi:10.3748/wjg.v21.i11.3330.
50 - Park KJ, Ryoo SB, Kim JS, Kim TI, Baik SH, Kim HJ, Lee KY, Kim M, Kim WH. Allogeneic adipose‐derived stem cells for the treatment of perianal fistula in Crohn’s disease: a pilot clinical trial. Colorectal Dis. 2015. doi:10.1111/codi.13223
51 - Barkholt L, Flory E, Jekerle V, Lucas‐Samuel S, Ahnert P, Bisset L, Büscher D, Fibbe W, Foussat A, Kwa M, Lantz O, Mačiulaitis R, Palomäki T, Schneider CK, Sensebé L, Tachdjian G, Tarte K, Tosca L, Salmikangas P. Risk of tumorigenicity in mesenchymal stromal cell‐based therapies‐‐bridging scientific observations and regulatory viewpoints. Cytotherapy. 2013;15(7):753–759. doi:10.1016/j.jcyt.2013.03.005
52 - García‐Olmo D, García‐Arranz M, García LG, Cuellar ES, Blanco IF, Prianes LA, Montes JA, Pinto FL, Marcos DH, García‐Sancho L. Autologous stem cell transplantation for treatment of rectovaginal fistula in perianal Crohn’s disease: a new cell‐based therapy. Int J Colorectal Dis. 2003;18(5):451–454. doi:10.1007/s00384‐003‐0490‐3
53 - Sanz‐Baro R, García‐Arranz M, Guadalajara H, de la Quintana P, Herreros MD, García‐Olmo D. First‐in‐human case study: pregnancy in women with Crohn’s perianal fistula treated with adipose‐derived stem cells: a safety study. Stem Cells Transl Med. 2015;4(6):598–602. doi:10.5966/sctm.2014‐0255