Functional outcome after anal sphincter injury and treatment with mesenchymal stem cells

3D spheroids versus 2D-cultured human adipose stem cells to generate smooth muscle cells in an internal anal sphincter-targeting cryoinjured mouse model

BACKGROUND

The efficacy of cell implantation via 3D-spheroids to treat basal tone in fecal incontinence remains unclear. To address this, in this study, we aimed to identify cell differentiation and assess the development of a contractile phenotype corresponding to smooth muscle cells (SMCs) following implantation of 3D-spheroid and 2D-cultured human adipose stem cells (hASCs) in an in vivo internal anal sphincter (IAS)-targeted mouse model.

METHODS

We developed an IAS-targeted in vivo model via rapid freezing (at - 196 °C) of the dorsal layers of the region of interest (ROI) of the IAS ring posterior quarter, between the submucosal and muscular layers, following submucosal dissection (n = 60 rats). After implantation of tetramethylindocarbocyanine perchlorate (Dil)-stained 3D and 2D-cells into randomly allocated cryoinjured rats, the entire sphincter ring or only the cryoinjured ROI was harvested. Expression of SMC markers, RhoA/ROCKII and its downstream molecules, and fibrosis markers was analyzed. Dil, α-smooth muscle actin (α-SMA), and RhoA signals were used for cell tracking.

RESULTS

In vitro, 3D-spheroids exhibited higher levels of SMC markers and RhoA/ROCKII-downstream molecules than 2D-hASCs. The IAS-targeted cryoinjured model exhibited substantial loss of SMC layers of the squamous epithelium lining of the anal canal, as well as reduced expression of SMC markers and RhoA-related downstream molecules. In vivo, 3D-spheroid implantation induced SMC markers and contractile molecules weakly at 1 week. At 2 weeks, the mRNA expression of aSma, Sm22a, Smoothelin, RhoA, Mypt1, Mlc20, Cpi17, and Pp1cd increased, whereas that of fibrosis markers reduced significantly in the 3D-spheroid implanted group compared to those in the sham, non-implanted, and 2D-hASC implanted groups. Protein levels of RhoA, p-MYPT1, and p-MLC20 were higher in the 3D-spheroid-implanted group than in the other groups. At 2 weeks, in the implanted groups, the cryoinjured tissues (which exhibited Dil, α-SMA, and RhoA signals) were restored, while they remained defective in the sham and non-implanted groups.

CONCLUSIONS

These findings demonstrate that, compared to 2D-cultured hASCs, 3D-spheroids more effectively induce a contractile phenotype that is initially weak but subsequently improves, inducing expression of RhoA/ROCKII-downstream molecules and SMC differentiation associated with IAS basal tone.

Muscle regeneration therapy using dedifferentiated fat cell (DFAT) for anal sphincter dysfunction

PURPOSE

We investigated the effects of mouse-derived DFAT on the myogenic differentiation of a mouse-derived myoblast cell line (C2C12) and examined the therapeutic effects of rat-derived DFAT on anal sphincter injury using a rat model.

METHODS

C2C12 cells were cultured using DMEM and DFAT-conditioned medium (DFAT-CM), evaluating MyoD and Myogenin gene expression via RT-PCR. DFAT was locally administered to model rats with anorectal sphincter dysfunction 3 days post-CTX injection. Therapeutic effects were assessed through functional assessment, including anal pressure measurement using solid-state manometry pre/post-CTX, and on days 1, 3, 7, 10, 14, 17, and 21 post-DFAT administration. Histological evaluation involved anal canal excision on days 1, 3, 7, 14, and 21 after CTX administration, followed by hematoxylin-eosin staining.

RESULTS

C2C12 cells cultured with DFAT-CM exhibited increased MyoD and Myogenin gene expression compared to control. Anal pressure measurements revealed early recovery of resting pressure in the DFAT-treated group. Histologically, DFAT-treated rats demonstrated an increase in mature muscle cells within newly formed muscle fibers on days 14 and 21 after CTX administration, indicating enhanced muscle tissue repair.

CONCLUSION

DFAT demonstrated the potential to enhance histological and functional muscle tissue repair. These findings propose DFAT as a novel therapeutic approach for anorectal sphincter dysfunction treatment.

Advances and clinical challenges of mesenchymal stem cell therapy

In recent years, cell therapy has provided desirable properties for promising new drugs. Mesenchymal stem cells are promising candidates for developing genetic engineering and drug delivery strategies due to their inherent properties, including immune regulation, homing ability and tumor tropism. The therapeutic potential of mesenchymal stem cells is being investigated for cancer therapy, inflammatory and fibrotic diseases, among others. Mesenchymal stem cells are attractive cellular carriers for synthetic nanoparticles for drug delivery due to their inherent homing ability. In this review, we comprehensively discuss the various genetic and non-genetic strategies of mesenchymal stem cells and their derivatives in drug delivery, tumor therapy, immune regulation, tissue regeneration and other fields. In addition, we discuss the current limitations of stem cell therapy and the challenges in clinical translation, aiming to identify important development areas and potential future directions.

Investigation of Expanded Human Adipose-derived Stem Cell Dosage and Timing for Improved Defecation Function

BACKGROUND/AIM

Although certain treatment options exist for intestinal incontinence, none are curative. Adipose-derived stem cells (ADSCs) have emerged as promising therapeutic agents, but most preclinical studies of their effectiveness for anal function have used autologous or allogeneic ADSCs. In this study, the effectiveness, timing of administration, and required dosage of human ADSCs were investigated for clinical application.

MATERIALS AND METHODS

A 10-mm balloon catheter was used to induce anal sphincter injury in immunodeficient mice in the following experimental groups (n=4 per group): ADSC (injected ADSCs after injury), PBS (injected phosphate-buffered saline after injury), and control (uninjured). The effects of different timing (immediately after injection and 30 days following injury) and number of human ADSCs administered was compared among groups based on defecation status and pathological evaluation.

RESULTS

In terms of defecation status, groups receiving ≥1×104 human ADSCs after injection showed improvement. Pathological images showed that compared to the PBS group, the thinnest part of the sphincter was thicker for animals that received ≥1×104 human ADSCs, and fibrosis of the sphincter was notable in those treated with 1×103 human ADSCs or PBS. Furthermore, defecation status was improved by administration of human ADSCs, not only immediately after injury, but also at 30 days following injury.

CONCLUSION

Human ADSC administration in a mouse model of anal sphincter injury was effective. Injection of ≥1×104 human ADSCs was the amount necessary to improve defecation status, an effect detected in both the acute and chronic phases.

Differentiation of Adipose-Derived Stem Cells into Smooth Muscle Cells in an Internal Anal Sphincter-Targeting Anal Incontinence Rat Model

OBJECTIVE

Studies on development of an anal incontinence (AI) model targeting smooth muscle cells (SMCs) of the internal anal sphincter (IAS) have not been reported. The differentiation of implanted human adipose-derived stem cells (hADScs) into SMCs in an IAS-targeting AI model has also not been demonstrated. We aimed to develop an IAS-targeting AI animal model and to determine the differentiation of hADScs into SMCs in an established model.

MATERIALS AND METHODS

The IAS-targeting AI model was developed by inducing cryoinjury at the inner side of the muscular layer via posterior intersphincteric dissection in Sprague-Dawley rats. Dil-stained hADScs were implanted at the IAS injury site. Multiple markers for SMCs were used to confirm molecular changes before and after cell implantation. Analyses were performed using H&E, immunofluorescence, Masson's trichrome staining, and quantitative RT-PCR.

RESULTS

Impaired smooth muscle layers accompanying other intact layers were identified in the cryoinjury group. Specific SMC markers, including SM22α, calponin, caldesmon, SMMHC, smoothelin, and SDF-1 were significantly decreased in the cryoinjured group compared with levels in the control group. However, CoL1A1 was increased significantly in the cryoinjured group. In the hADSc-treated group, higher levels of SMMHC, smoothelin, SM22α, and α-SMA were observed at two weeks after implantation than at one week after implantation. Cell tracking revealed that Dil-stained cells were located at the site of augmented SMCs.

CONCLUSIONS

This study first demonstrated that implanted hADSc restored impaired SMCs at the injury site, showing stem cell fate corresponding to the established IAS-specific AI model.

The Effect of Tissue Stromal Vascular Fraction as Compared to Cellular Stromal Vascular Fraction to Treat Anal Sphincter Incontinence

BACKGROUND

The long-term prognosis of current treatments for anal sphincter incontinence (ASI) is poor. Here, we explored the efficacy of tissue adipose stromal vascular fraction SVF (tSVF) on ASI and compared it to that of cellular SVF (cSVF). We then investigated possible mechanisms.

METHODS

Rat cSVF and tSVF were isolated and labeled with DIL. One day after modeling, three groups received phosphate-buffered saline (PBS), cSVF, tSVF, respectively. The control group received nil modeling nor any treatments. The effect was assessed by function test for anal pressure and electromyography, and staining for fiber content, proliferation and differentiation at day 5 and day 10.

RESULTS

cSVF injection resulted in faster healing than tSVF. The cSVF group showed significant improvement on anal pressure on day 10. For the electromyography test, cSVF showed significant improvement for the frequencies on day 10, and for the peak values on both time points, while tSVF showed significant improvement for the peak values on day 10. The two SVF both alleviated fibrosis. Immunofluorescence tracing identified differentiation of some injected cells towards myosatellite cells and smooth muscle cells in both SVF groups. For all the tests, the tSVF group tends to have similar or lower effects than the cSVF group with no significant difference.

CONCLUSION

cSVF and tSVF are both safe and effective in treating ASI, while the effect of cSVF is slighter higher than tSVF.

The Effect of Mesenchymal Stem Cells, Adipose Tissue Derived Stem Cells, and Cellular Stromal Vascular Fraction on the Repair of Acute Anal Sphincter Injury in Rats

Background: Anal sphincter incontinence (ASI) can cause a serious decline in the quality of life and can cause a socioeconomic burden. Studies have shown that bone marrow mesenchymal stem cells (MSC) have significant therapeutic effects on ASI, but the cost and risk of MSC harvest limit their further application. In contrast, adipose tissue derived stem cells (ADSC) and cellular stromal vascular fraction (CSVF) as stem cell sources have multipotency and the advantage of easy harvest. Objective: Here we aim to investigate the effects of ADSC and CSVF on treating ASI and compare them to that of bone marrow MSC. Methods: Bone marrow MSC, ADSC, and CSVF were obtained and labeled with green fluorescent protein (GFP), and CSVF was labeled with DIL. Sprague Dawley (SD) rats were divided into 5 groups. Four groups were injected with 0.2 mL phosphate buffer saline (PBS), 1 × 107/0.2 mL of MSC, ADSC, or CSVF, respectively, after model establishment. The control group received no treatment. The repair was assessed by anal functional tests and immunostaining on day 5 and day 10 after injection. Results: MSC, ADSC, and CSVF significantly promoted tissue repair and the recovery of muscle contraction and electromyographic activity in ASI. The generation of myosatellite cells by injected MSC, ADSC, and CSVF was found in the wounded area. On day 5, CSVF showed highest therapeutic effect, while on day 10, MSC and ADSC showed higher therapeutic effects than CSVF. When comparing the effects of MSC and ADSC, ADSC was slightly better than MSC in the indexes of anal pressure, etc. Conclusion: ADSC and CVSF are alternative stem cell sources for ASI repair.

A systematic review of translation and experimental studies on internal anal sphincter for fecal incontinence

The complexity in the molecular mechanism of the internal anal sphincter (IAS) limits preclinical or clinical outcomes of fecal incontinence (FI) treatment. So far, there are no systematic reviews of IAS translation and experimental studies that have been reported. This systematic review aims to provide a comprehensive understanding of IAS critical role in FI. Previous studies revealed the key pathway for basal tone and relaxation of IAS in different properties as follows; calcium, Rho-associated, coiled-coil containing serine/threonine kinase, aging-associated IAS dysfunction, oxidative stress, renin-angiotensin-aldosterone, cyclooxygenase, and inhibitory neurotransmitters. Previous studies have reported improved functional outcomes of cellular treatment for regeneration of dysfunctional IAS, using various stem cells, but did not demonstrate the interrelationship between those results and basal tone or relaxation-related molecular pathway of IAS. Furthermore, these results have lower specificity for IAS-incontinence due to the included external anal sphincter or nerve injury regardless of the cell type. An acellular approach using bioengineered IAS showed a physiologic response of basal tone and relaxation response similar to human IAS. However, in both cellular and acellular approaches, the lack of human IAS data still hampers clinical application. Therefore, the IAS regeneration presents more challenges and warrants more advances.

Intestinal Fibrosis in Inflammatory Bowel Disease and the Prospects of Mesenchymal Stem Cell Therapy

Intestinal fibrosis is an important complication of inflammatory bowel disease (IBD). In the course of the development of fibrosis, certain parts of the intestine become narrowed, significantly destroying the structure and function of the intestine and affecting the quality of life of patients. Chronic inflammation is an important initiating factor of fibrosis. Unfortunately, the existing anti-inflammatory drugs cannot effectively prevent and alleviate fibrosis, and there is no effective anti-fibrotic drug, which makes surgical treatment the mainstream treatment for intestinal fibrosis and stenosis. Mesenchymal stem cells (MSCs) are capable of tissue regeneration and repair through their self-differentiation, secretion of cytokines, and secretion of extracellular vesicles. MSCs have been shown to play an important therapeutic role in the fibrosis of many organs. However, the role of MSC in intestinal fibrosis largely remained unexplored. This review summarizes the mechanism of intestinal fibrosis, including the role of immune cells, TGF-β, and the gut microbiome and metabolites. Available treatment options for fibrosis, particularly, MSCs are also discussed.

Stromal cell derived factor 1 plasmid to regenerate the anal sphincters

The aim of this study was to evaluate regeneration of a chronic large anal sphincter defect in a pig model after treatment with a plasmid encoding Stromal Cell Derived Factor-1(SDF-1).

METHODS

Under ethics approved protocol 19 age/weight matched Sinclair mini-pigs were subjected to excision of the posterior 50% of anal sphincter muscle and left to recover for 6 weeks. They were randomly allocated to receive either saline treatment (Saline 1 ml, n = 5), 1 injection of SDF-1 plasmid 2 mg/ml (1 SDF-1, n = 9) or 2 injections of SDF-1, 2 mg/ml each at 2 weeks intervals (2 SDF-1, n = 5). Euthanasia occurred 8 weeks after the last treatment. In vivo outcomes included anal resting pressures done under anesthesia pre-injury, pre-injection and before euthanasia (8 weeks after treatment). Anal ultrasound was done pre injury and pre-euthanasia. Tissues were saved for histology and analyzed quantitatively. Two way ANOVA followed by Holm-Sidak test and one way ANOVA followed by the Tukey test were used for data analysis, p < 0.05 was regarded as significant.

RESULTS

Posterior anal pressures at the 3 time points were not significantly different in the saline group. In contrast, post-treatment pressures in the 1 SDF-1 group pressures were significantly higher than both pre-injury (p = 0.001) and pre-treatment time points (p = 0.003). At the post-treatment time point, both 1 SDF-1 (p = 0.01) and 2 SDF-1 (p = 0.01) groups had significantly higher mean pressures compared to the saline group. Histology showed distortion of normal anatomy with patchy regeneration in the control group while muscle was more organized in both treatment groups.

CONCLUSIONS

Eight weeks after a single or two doses of SDF-1injected into a chronic anal sphincter injury improved resting anal pressures and regenerated muscle in the entire defect. SDF-1 plasmid is effective in treating chronic defects of the anal sphincter in a large animal and could be clinically translated.

Cell Therapy for Anal Sphincter Incontinence: Where Do We Stand?

Anal sphincter incontinence is a chronic disease, which dramatically impairs quality of life and induces high costs for the society. Surgery, considered as the best curative option, shows a disappointing success rate. Stem/progenitor cell therapy is pledging, for anal sphincter incontinence, a substitute to surgery with higher efficacy. However, the published literature is disparate. Our aim was to perform a review on the development of cell therapy for anal sphincter incontinence with critical analyses of its pitfalls. Animal models for anal sphincter incontinence were varied and tried to reproduce distinct clinical situations (acute injury or healed injury with or without surgical reconstruction) but were limited by anatomical considerations. Cell preparations used for treatment, originated, in order of frequency, from skeletal muscle, bone marrow or fat tissue. The characterization of these preparations was often incomplete and stemness not always addressed. Despite a lack of understanding of sphincter healing processes and the exact mechanism of action of cell preparations, this treatment was evaluated in 83 incontinent patients, reporting encouraging results. However, further development is necessary to establish the correct indications, to determine the most-suited cell type, to standardize the cell preparation method and to validate the route and number of cell delivery.

Regenerative medicine for anal incontinence: a review of regenerative therapies beyond cells

INTRODUCTION AND HYPOTHESIS

Current treatment modalities for anal sphincter injuries are ineffective for many patients, prompting research into restorative and regenerative therapies. Although cellular therapy with stem cells and progenitor cells show promise in animal models with short-term improvement, there are additional regenerative approaches that can augment or replace cellular therapies for anal sphincter injuries. The purpose of this article is to review the current knowledge of cellular therapies for anal sphincter injuries and discusses the use of other regenerative therapies including cytokine therapy with CXCL12.

METHODS

A literature search was performed to search for articles on cellular therapy and cytokine therapy for anal sphincter injuries and anal incontinence.

RESULTS

The article search identified 337 articles from which 33 articles were included. An additional 12 referenced articles were included as well as 23 articles providing background information. Cellular therapy has shown positive results for treating anal sphincter injuries and anal incontinence in vitro and in one clinical trial. However, cellular therapy has disadvantages such as the source and processing of stem cells and progenitor cells. CXCL12 does not have such issues while showing promising in vitro results for treating anal sphincter injuries. Additionally, electrical stimulation and extracorporeal shock wave therapy are potential regenerative medicine adjuncts for anal sphincter injuries. A vision for future research and clinical applications of regenerative medicine for anal sphincter deficiencies is provided.

CONCLUSION

There are viable regenerative medicine therapies for anal sphincter injuries beyond cellular therapy. CXCL12 shows promise as a focus of therapeutic research in this field.

MSC-based therapy in female pelvic floor disorders

Mesenchymal stem cells (MSCs), also referred to as multipotent stromal cells or mesenchymal stromal cells, are present in multiple tissues and capable of differentiating into diverse cell lineages, holding a great promise in developing cell-based therapy for a wide range of conditions. Pelvic floor disorders (PFDs) is a common degenerative disease in women and may diminish a woman's quality of life at any age. Since the treatments for this disease are limited by the high rates of recurrence and surgical complications, seeking an ideal therapy in the restoration of pelvic floor function is an urgent issue at present. Herein, we summarize the cell sources of MSCs used for PFDs and discuss the potential mechanisms of MSCs in treating PFDs. Specifically, we also provide a comprehensive review of current preclinical and clinical trials dedicated to investigating MSC-based therapy for PFDs. The novel therapy has presented promising therapeutic effects which include relieving the symptoms of urinary or fecal incontinence, improving the biological properties of implanted meshes and promoting the injured tissue repair. Nevertheless, MSC-based therapies for PFDs are still experimental and the unstated issues on their safety and efficacy should be carefully addressed before their clinical applications.

Combined Treatment With CCR1-Overexpressing Mesenchymal Stem Cells and CCL7 Enhances Engraftment and Promotes the Recovery of Simulated Birth Injury-Induced Stress Urinary Incontinence in Rats

Objective: To observe whether urethral injection of chemokine (c-c motif) ligand 7 (CCL7) and overexpressing CC receptor 1 (CCR1) in mesenchymal stem cells (MSCs) can promote their homing and engraftment to the injured tissue, and improve the recovery of simulated birth injury-induced stress urinary incontinence (SUI) in rats.

Methods: Female rats underwent a dual injury consisting of vaginal distension (VD) and pudendal nerve crush (PNC) to induce SUI. Bone marrow-derived MSCs were transduced with lentivirus carrying CCR1 (MSC-CCR1) and green fluorescent protein (GFP). Forty virgin Sprague–Dawley rats were evenly distributed into four groups: sham SUI + MSC-CCR1+CCL7, SUI + MSCs, SUI + MSC-CCR1, and SUI + MSC-CCR1+CCL7 group. The engrafted MSCs in urethra were quantified. Another three groups of rats, including sham SUI + sham MSC-CCR1+CCL7 treatment, SUI + sham MSC-CCR1+CCL7 treatment, and SUI + MSC-CCR1+CCL7 treatment group, were used to evaluate the functional recovery by testing external urethral sphincter electromyography (EUS EMG), pudendal nerve motor branch potentials (PNMBP), and leak point pressure (LPP) 1 week after injury and injection. Urethra and vagina were harvested for histological examination.

Results: The SUI + MSC-CCR1+CCL7 group received intravenous injection of CCR1-overexpressing MSCs and local injection of CCL7 after simulated birth injury had the most engraftment of MSCs to the injured tissues and best functional recovery from SUI compared to other groups. Histological examination showed a partial repair in the SUI + MSC-CCR1+CCL7 group.

Conclusions: Our study demonstrated combined treatment with CCR1-overexpressing MSCs and CCL7 can increase engraftment of MSCs and promote the functional recovery of simulated birth trauma-induced SUI in rats, which could be a new therapeutic strategy for SUI.

Effects of local injection and intravenous injection of allogeneic bone marrow mesenchymal stem cells on the structure and function of damaged anal sphincter in rats

Anal sphincter injury leads to damage to the anal structure and functions and has been identified as a major risk factor for fecal incontinence. Bone marrow mesenchymal stem cells (BMSCs) with capacities of multidifferentiation, paracrine, and low immunogenicity have been widely used in tissue repair and regeneration. The primary objective of this research was to compare the effects of different injection therapies of BMSCs on the injured anal sphincters. Ninety-six Sprague-Dawley female rats were randomly divided into four groups (n = 24 each): intravenous injection, local injection, sham operation, and normal control. For the first three groups, 25% removal of the anal sphincter complex was performed and 0.3-ml phosphate-buffered saline (PBS) (containing 10⁷ green fluorescent protein-labeled allogeneic BMSCs) was given accordingly to the treatment group 24 h after operation for 7 consecutive days. The sham operation group was injected with 0.3-ml PBS only. All cases had undergone evaluation in the 1st, 7th, 14th, and 28th postoperative days. The rats were sacrificed on the 28th postoperative day, and the anal sphincters were dissected to be analyzed by morphological examination. At 14 days postoperatively, local injection of BMSC significantly improved the peak contraction pressure, electromyography amplitude, and frequency of the injured anal sphincter compared with tail vein, but there was no significant difference in resting pressure until 28 days after sphincterectomy. Masson staining results confirmed that the local injection group had significantly more new muscles on the wound. BMSC could remarkably improve peak contraction pressure, electromyography amplitude, and muscle fibers on the wound, and local injection is superior to intravenous injection.

Generation of myogenic progenitor cell-derived smooth muscle cells for sphincter regeneration

BACKGROUND

Degeneration of smooth muscles in sphincters can cause debilitating diseases such as fecal incontinence. Skeletal muscle-derived cells have been effectively used in clinics for the regeneration of the skeletal muscle sphincters, such as the external anal or urinary sphincter. However, little is known about the in vitro smooth muscle differentiation potential and in vivo regenerative potential of skeletal muscle-derived cells.

METHODS

Myogenic progenitor cells (MPC) were isolated from the skeletal muscle and analyzed by flow cytometry and in vitro differentiation assays. The differentiation of MPC to smooth muscle cells (MPC-SMC) was evaluated by immunofluorescence, flow cytometry, patch-clamp, collagen contraction, and microarray gene expression analysis. In vivo engraftment of MPC-SMC was monitored by transplanting reporter protein-expressing cells into the pyloric sphincter of immunodeficient mice.

RESULTS

MPC derived from human skeletal muscle expressed mesenchymal surface markers and exhibit skeletal myogenic differentiation potential in vitro. In contrast, they lack hematopoietic surface marker, as well as adipogenic, osteogenic, and chondrogenic differentiation potential in vitro. Cultivation of MPC in smooth muscle differentiation medium significantly increases the fraction of alpha smooth muscle actin (aSMA) and smoothelin-positive cells, while leaving the number of desmin-positive cells unchanged. Smooth muscle-differentiated MPC (MPC-SMC) exhibit increased expression of smooth muscle-related genes, significantly enhanced numbers of CD146- and CD49a-positive cells, and in vitro contractility and express functional Cav and Kv channels. MPC to MPC-SMC differentiation was also accompanied by a reduction in their skeletal muscle differentiation potential. Upon removal of the smooth muscle differentiation medium, a major fraction of MPC-SMC remained positive for aSMA, suggesting the definitive acquisition of their phenotype. Transplantation of murine MPC-SMC into the mouse pyloric sphincter revealed engraftment of MPC-SMC based on aSMA protein expression within the host smooth muscle tissue.

CONCLUSIONS

Our work confirms the ability of MPC to give rise to smooth muscle cells (MPC-SMC) with a well-defined and stable phenotype. Moreover, the engraftment of in vitro-differentiated murine MPC-SMC into the pyloric sphincter in vivo underscores the potential of this cell population as a novel cell therapeutic treatment for smooth muscle regeneration of sphincters.

BioSphincters to treat Fecal Incontinence in Nonhuman Primates

Loss of anorectal resting pressure due to internal anal sphincter (IAS) dysfunctionality causes uncontrolled fecal soiling and leads to passive fecal incontinence (FI). The study is focused on immediate and long-term safety and potential efficacy of bioengineered IAS BioSphincters to treat passive FI in a clinically relevant large animal model of passive FI. Passive FI was successfully developed in Non-Human Primates (NHPs) model. The implantation of autologous intrinsically innervated functional constructs resolved the fecal soiling, restored the resting pressure and Recto Anal Inhibitory Reflex (RAIR) within 1-month. These results were sustained with time, and efficacy was preserved up to 12-months. The histological studies validated manometric results with the regeneration of a well-organized neuro-muscular population in IAS. The control groups (non-treated and sham) remained affected by poor anal hygiene, lower resting pressure, and reduced RAIR throughout the study. The pathological assessment of implants, blood, and the vital organs confirmed biocompatibility without any adverse effect after implantation. This regenerative approach of implanting intrinsically innervated IAS BioSphincters has the potential to offer a better quality of life to the patients suffering from FI.

Regenerative medicine as a therapeutic option for fecal incontinence: a systematic review of preclinical and clinical studies

BACKGROUND

Fecal incontinence is the uncontrollable loss of stool and has a prevalence of around 7-15%. This condition has serious implications for patients' quality of life. Current treatment options show unsatisfactory results. A novel treatment option is therefore needed.

OBJECTIVE

This systematic review aims to perform a quality assessment and to give a critical overview of the current research available on regenerative medicine as a treatment for fecal incontinence.

STUDY DESIGN

A systematic search strategy was applied in PubMed, Cochrane Library, EMBASE, MEDLINE, Web of Science, and Cinahl from inception until March of 2018. Studies were found relevant when the animals or patients in the studied group had objectively determined or induced fecal incontinence, and the intervention must have used any kind of cells, stem cells, or biocompatible material, with or without the use of trophic factors. Studies were screened on title and consecutively on abstract for relevance by 2 independent investigators. The risk of bias of preclinical studies was assessed using the SYstematic Review Centre for Laboratory animal Experimentation risk of bias tool for animal studies, and for clinical studies the Cochrane risk of bias tool for randomized trials was used.

RESULTS

In all, 34 preclinical studies and 5 clinical studies were included. Animal species, type of anal sphincter injury, intervention, and outcome parameters were heterogenous. Therefore, a meta-analysis could not be performed. The overall risk of bias of the included studies was high.

CONCLUSION

The efficacy of regenerative medicine to treat fecal incontinence could not be determined due to the high risk of bias and heterogenicity of the available preclinical and clinical studies. The findings of this systematic review may result in improved study design of future studies, which could help the translation of regenerative medicine to the clinic as an alternative to current treatments for fecal incontinence.

Stem cell therapy for faecal incontinence: Current state and future perspectives

Faecal continence is a complex function involving different organs and systems. Faecal incontinence is a common disorder with different pathogeneses, disabling consequences and high repercussions for quality of life. Current management modalities are not ideal, and the development of new treatments is needed. Since 2008, stem cell therapies have been validated, 36 publications have appeared (29 in preclinical models and seven in clinical settings), and six registered clinical trials are currently ongoing. Some publications have combined stem cells with bioengineering technologies. The aim of this review is to identify and summarise the existing published knowledge of stem cell utilization as a treatment for faecal incontinence. A narrative or descriptive review is presented. Preclinical studies have demonstrated that cellular therapy, mainly in the form of local injections of muscle-derived (muscle derived stem cells or myoblasts derived from them) or mesenchymal (bone-marrow- or adipose-derived) stem cells, is safe. Cellular therapy has also been shown to stimulate the repair of both acute and subacute anal sphincter injuries, and some encouraging functional results have been obtained. Stem cells combined with normal cells on bioengineered scaffolds have achieved the successful creation and implantation of intrinsically-innervated anal sphincter constructs. The clinical evidence, based on adipose-derived stem cells and myoblasts, is extremely limited yet has yielded some promising results, and appears to be safe. Further investigation in both animal models and clinical settings is necessary to drawing conclusions. Nevertheless, if the preliminary results are confirmed, stem cell therapy for faecal incontinence may well become a clinical reality in the near future.

Functional and histologic effects after implanting pluripotent stem cells in a murine model with sphincterotomy

INTRODUCTION AND AIMS

Fecal incontinence is a disabling condition with devastating consequences for the patients. Medical and surgical options are not very satisfactory, reason by which regenerative medicine has been considered in this field. In the present research, we analyzed functional and histologic effects after implanting pluripotent stem cells (PSCs) in a murine model with sphincterotomy.

MATERIALS AND METHODS

Female Wistar rats were subjected to sphincterotomy and divided into three groups. Group 1 (control group) was treated with 300μL of balanced saline solution and group 2 (late treatment) and group 3 (early treatment) received 50,000 PSCs resuspended in 300μL of balanced saline solution. All animals were evaluated through high-resolution anorectal manometry 24hours before and after sphincterotomy and every month for three months. Finally, the rats were euthanized and histopathologic sections from the anal canal were obtained.

RESULTS

All groups showed a decrease in resting anal pressure and squeeze anal pressure 24hours after sphincterotomy. At the third month, higher anal pressures in the groups treated with PSCs were detected. Regarding the histologic effects, the microscopic architecture was restored and there was a significant decrease in the inflammatory response in the groups treated with PSCs.

CONCLUSION

PSCs implantation improves anal tone, as well as histologic structure, presenting better regenerative results when implanted as early treatment.

Functional Outcome of Human Adipose Stem Cell Injections in Rat Anal Sphincter Acute Injury Model

Anal incontinence is a devastating condition that significantly reduces the quality of life. Our aim was to evaluate the effect of human adipose stem cell (hASC) injections in a rat model for anal sphincter injury, which is the main cause of anal incontinence in humans. Furthermore, we tested if the efficacy of hASCs could be improved by combining them with polyacrylamide hydrogel carrier, Bulkamid. Human ASCs derived from a female donor were culture expanded in DMEM/F12 supplemented with human platelet lysate. Female virgin Sprague‐Dawley rats were randomized into four groups (n = 14–15/group): hASCs in saline or Bulkamid (3 × 10⁵/60 μl) and saline or Bulkamid without cells. Anorectal manometry (ARM) was performed before anal sphincter injury, at two (n = 58) and at four weeks after (n = 33). Additionally, the anal sphincter tissue was examined by micro‐computed tomography (μCT) and the histological parameters were compared between the groups. The median resting and peak pressure during spontaneous contraction measured by ARM were significantly higher in hASC treatment groups compared with the control groups without hASCs. There was no statistical difference in functional results between the hASC‐carrier groups (saline vs. Bulkamid). No difference was detected in the sphincter muscle continuation between the groups in the histology and μCT analysis. More inflammation was discovered in the group receiving saline with hASC. The hASC injection therapy with both saline and Bulkamid is a promising nonsurgical treatment for acute anal sphincter injury. Traditional histology combined with the 3D μCT image data lends greater confidence in assessing muscle healing and continuity. Stem Cells Translational Medicine2018;7:295–304

Rat model of anal sphincter injury and two approaches for stem cell administration

AIM

To establish a rat model of anal sphincter injury and test different systems to provide stem cells to injured area.

METHODS

Adipose-derived stem cells (ASCs) were isolated from BDIX rats and were transfected with green fluorescent protein (GFP) for cell tracking. Biosutures (sutures covered with ASCs) were prepared with 1.5 x 10⁶ GFP-ASCs, and solutions of 10⁶ GFP-ASCs in normal saline were prepared for injection. Anorectal normal anatomy was studied on Wistar and BDIX female rats. Then, we designed an anal sphincter injury model consisting of a 1-cm extra-mucosal miotomy beginning at the anal verge in the anterior middle line. The sphincter lesion was confirmed with conventional histology (hematoxylin and eosin) and immunofluorescence with 4', 6-diamidino-2-phenylindole (commonly known as DAPI), GFP and α-actin. Functional effect was assessed with basal anal manometry, prior to and after injury. After sphincter damage, 36 BDIX rats were randomized to three groups for: (1) Cell injection without repair; (2) biosuture repair; and (3) conventional suture repair and cell injection. Functional and safety studies were conducted on all the animals. Rats were sacrificed after 1, 4 or 7 d. Then, histological and immunofluorescence studies were performed on the surgical area.

RESULTS

With the described protocol, biosutures had been covered with at least 820000-860000 ASCs, with 100% viability. Our studies demonstrated that some ASCs remained adhered after suture passage through the muscle. Morphological assessment showed that the rat anal anatomy is comparable with human anatomy; two sphincters are present, but the external sphincter is poorly developed. Anal sphincter pressure data showed spontaneous, consistent, rhythmic anal contractions, taking the form of “plateaus” with multiple twitches (peaks) in each pressure wave. These basal contractions were very heterogeneous; their frequency was 0.91-4.17 per min (mean 1.6980, SD 0.57698), their mean duration was 26.67 s and mean number of peaks was 12.53. Our morphological assessment revealed that with the aforementioned surgical procedure, both sphincters were completely sectioned. In manometry, the described activity disappeared and was replaced by a gentle oscillation of basal line, without a recognizable pattern. Surprisingly, these findings appeared irrespective of injury repair or not. ASCs survived in this potentially septic area for 7 d, at least. We were able to identify them in 84% of animals, mainly in the muscular section area or in the tissue between the muscular endings. ASCs formed a kind of “conglomerate” in rats treated with injections, while in the biosuture group, they wrapped the suture. ASCs were also able to migrate to the damaged zone. No relevant adverse events or mortality could be related to the stem cells in our study. We also did not find unexpected tissue growths.

CONCLUSION

The proposed procedure produces a consistent sphincter lesion. Biosutures and injections are suitable for cell delivery. ASCs survive and are completely safe in this clinical setting.

Stromal Cell-Derived Factor 1 Plasmid Regenerates Both Smooth and Skeletal Muscle After Anal Sphincter Injury in the Long Term

BACKGROUND

Regenerating muscle at a time remote from injury requires re-expression of cytokines to attract stem cells to start and sustain the process of repair.

OBJECTIVE

We aimed to evaluate the sustainability of muscle regeneration after treatment with a nonviral plasmid expressing stromal cell-derived factor 1.

DESIGN

This was a randomized study.

SETTINGS

The study was conducted with animals in a single research facility.

INTERVENTIONS

Fifty-six female age-/weight-matched Sprague-Dawley rats underwent excision of the ventral half of the anal sphincter complex. Three weeks later, rats were randomly allocated (n = 8) to one of the following groups: no treatment, 100 μg of plasmid encoding stromal cell-derived factor 1 injected locally, local injection of plasmid and 8 × 10 bone marrow-derived mesenchymal stem cells, and plasmid encoding stromal cell-derived factor 1 injected locally with injection of a gelatin scaffold mixed with bone marrow-derived mesenchymal stem cells.

MAIN OUTCOME MEASURES

Anal manometry, histology, immunohistochemistrym and morphometry were performed 8 weeks after treatment. Protein expression of cytokines CXCR4 and Myf5 was investigated 1 week after treatment (n = 6 per group). ANOVA was used, with p < 0.0083 indicating significant differences for anal manometry and p < 0.05 for all other statistical analysis.

RESULTS

Eight weeks after treatment, all of the groups receiving the plasmid had significantly higher anal pressures than controls and more organized muscle architecture in the region of the defect. Animals receiving plasmid alone had significantly greater muscle in the defect (p = 0.03) than either animals with injury alone (p = 0.02) or those receiving the plasmid, cells, and scaffold (p = 0.03). Both smooth and skeletal muscles were regenerated significantly more after plasmid treatment. There were no significant differences in the protein levels of CXCR4 or Myf5.

LIMITATIONS

The study was limited by its small sample size and because stromal cell-derived factor 1 was not blocked.

CONCLUSIONS

A plasmid expressing stromal cell-derived factor 1 may be sufficient to repair an injured anal sphincter even long after the injury and in the absence of mesenchymal stem cell or scaffold treatments. See Video Abstract at http://links.lww.com/DCR/A451.

Systematic Review of Animal Models Used in Research of Origins and Treatments of Fecal Incontinence

BACKGROUND

Fecal incontinence is a common disorder, but its pathophysiology is not completely understood.

OBJECTIVE

The aim of this review is to present animal models that have a place in the study of fecal incontinence.

DATA SOURCES

A literature review following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines performed in August 2016 revealed 50 articles of interest. Search terms included fecal/faecal incontinence and animal model or specific species.

STUDY SELECTION

Articles not describing an animal model, in vitro studies, veterinary literature, reviews, and non-English articles were excluded.

MAIN OUTCOME MEASURES

The articles described models in rats (n = 31), dogs (n = 8), rabbits (n = 7), and pigs (n = 4).

RESULTS

Different fecal incontinence etiologies were modeled, including anal sphincter lesions (33 articles) ranging from a single anal sphincter cut to destruction of 50% of the anal sphincter by sharp dissection, electrocautery, or diathermy. Neuropathic fecal incontinence (12 articles) was achieved by complete or incomplete pudendal, pelvic, or inferior rectal nerve damage. Mixed fecal incontinence (5 articles) was modeled either by the inflation of pelvic balloons or an array of several lesions including nervous and muscular damage. Anal fistulas (2 articles), anal sphincter resection (3 articles), and diabetic neuropathy (2 articles) were studied to a lesser extent.

LIMITATIONS

Bias may have arisen from the authors' own work on fecal incontinence and the absence of blinding to the origins of articles.

CONCLUSIONS

Validated animal models representing the main etiologies of fecal incontinence exist, but no animal model to date represents the whole pathophysiology of fecal incontinence. Therefore, the individual research questions still dictate the choice of model and species.

Cell-based secondary prevention of childbirth-induced pelvic floor trauma

With advancing population age, pelvic-floor dysfunction (PFD) will affect an increasing number of women. Many of these women wish to maintain active lifestyles, indicating an urgent need for effective strategies to treat or, preferably, prevent the occurrence of PFD. Childbirth and pregnancy have both long been recognized as crucial contributing factors in the pathophysiology of PFD. Vaginal delivery of a child is a serious traumatic event, causing anatomical and functional changes in the pelvic floor. Similar changes to those experienced during childbirth can be found in symptomatic women, often many years after delivery. Thus, women with such PFD symptoms might have incompletely recovered from the trauma caused by vaginal delivery. This hypothesis creates the possibility that preventive measures can be initiated around the time of delivery. Secondary prevention has been shown to be beneficial in patients with many other chronic conditions. The current general consensus is that clinicians should aim to minimize the extent of damage during delivery, and aim to optimize healing processes after delivery, therefore preventing later dysfunction. A substantial amount of research investigating the potential of stem-cell injections as a therapeutic strategy for achieving this purpose is currently ongoing. Data from small animal models have demonstrated positive effects of mesenchymal stem-cell injections on the healing process following simulated vaginal birth injury.

Regenerating the Anal Sphincter: Cytokines, Stem Cells, or Both?

BACKGROUND

Healing of an anal sphincter defect at a time distant from injury is a challenge.

OBJECTIVE

We aimed to investigate whether re-establishing stem cell homing at the site of an anal sphincter defect when cytokine expression has declined using a plasmid engineered to express stromal derived factor 1 with or without mesenchymal stem cells can improve anatomic and functional outcome.

DESIGN

This was a randomized animal study.

SETTINGS

Thirty-two female age- and weight-matched Sprague Dawley rats underwent 50% excision of the anal sphincter complex. Three weeks after injury, 4 interventions were randomly allocated (n = 8), including no intervention, 100-μg plasmid, plasmid and 800,000 cells, and plasmid with a gelatin scaffold mixed with cells.

MAIN OUTCOME MEASURES

The differences in anal sphincter resting pressures just before and 4 weeks after intervention were used for functional analysis. Histology was analyzed using Masson staining. One-way ANOVA followed by the Tukey post hoc test was used for pressure and histological analysis.

RESULTS

All 3 of the intervention groups had a significantly greater change in resting pressure (plasmid p = 0.009; plasmid + cells p = 0.047; plasmid + cells in scaffold p = 0.009) compared with the control group. The plasmid-with-cells group showed increased organization of muscle architecture and increased muscle percentage, whereas the control group showed disorganized architecture at the site of the defect. Histological quantification revealed significantly more muscle at the site of defect in the plasmid-plus-cells group compared with the control group, which had the least muscle. Quantification of connective tissue revealed significantly less fibrosis at the site of defect in the plasmid and plasmid-plus-cells groups compared with the control group.

LIMITATIONS

Midterm evaluation and muscle morphology were not defined.

CONCLUSIONS

At this midterm follow-up, local delivery of a stromal derived factor 1 plasmid with or without local mesenchymal stem cells enhanced anal sphincter muscle regeneration long after an anal sphincter injury, thereby improving functional outcome. See Video Abstract at http://links.lww.com/DCR/A324.

Regenerative medicine provides alternative strategies for the treatment of anal incontinence

INTRODUCTION AND HYPOTHESIS

Anal incontinence is a common disorder but current treatment modalities are not ideal and the development of new treatments is needed. The aim of this review was to identify the existing knowledge of regenerative medicine strategies in the form of cellular therapies or bioengineering as a treatment for anal incontinence caused by anal sphincter defects.

METHODS

PubMed was searched for preclinical and clinical studies in English published from January 2005 to January 2016.

RESULTS

Animal studies have demonstrated that cellular therapy in the form of local injections of culture-expanded skeletal myogenic cells stimulates repair of both acute and 2 - 4-week-old anal sphincter injuries. The results from a small clinical trial with ten patients and a case report support the preclinical findings. Animal studies have also demonstrated that local injections of mesenchymal stem cells stimulate repair of sphincter injuries, and a complex bioengineering strategy for creation and implantation of an intrinsically innervated internal anal sphincter construct has been successfully developed in a series of animal studies.

CONCLUSION

Cellular therapies with myogenic cells and mesenchymal stem cells and the use of bioengineering technology to create an anal sphincter are new potential strategies to treat anal incontinence caused by anal sphincter defects, but the clinical evidence is extremely limited. The use of culture-expanded autologous skeletal myogenic cells has been most intensively investigated and several clinical trials were ongoing at the time of this report. The cost-effectiveness of such a therapy is an issue and muscle fragmentation is suggested as a simple alternative.

Electrical Stimulation Followed by Mesenchymal Stem Cells Improves Anal Sphincter Anatomy and Function in a Rat Model at a Time Remote From Injury

BACKGROUND

We have explored cell-based therapy to aid anal sphincter repair, but a conditioning injury is required to direct stem cells to the site of injury because symptoms usually manifest at a time remote from injury.

OBJECTIVE

We aimed to investigate the effect of local electrical stimulation followed by mesenchymal stem cell delivery on anal sphincter regeneration at a time remote from injury.

DESIGN AND MAIN OUTCOME MEASURES

With the use of a rat model, electrical stimulation parameters and cell delivery route were selected based on in vivo cytokine expression and luciferase-labeled cell imaging of the anal sphincter complex. Three weeks after a partial anal sphincter excision, rats were randomly allocated to 4 groups based on different local interventions: no treatment, daily electrical stimulation for 3 days, daily stimulation for 3 days followed by stem cell injection on the third day, and daily electrical stimulation followed by stem cell injection on the first and third days. Histology-assessed anatomy and anal manometry evaluated physiology 4 weeks after intervention.

RESULTS

The electrical stimulation parameters that significantly upregulated gene expression of homing cytokines also achieved mesenchymal stem cell retention when injected directly in the anal sphincter complex in comparison with intravascular and intraperitoneal injections. Four weeks after intervention, there was significantly more new muscle in the area of injury and significantly improved anal resting pressure in the group that received daily electrical stimulation for 3 days followed by a single injection of 1 million stem cells on the third day at the site of injury.

LIMITATION

This was a pilot study and therefore was not powered for functional outcome.

CONCLUSIONS

In this rat injury model with optimized parameters, electrical stimulation with a single local mesenchymal stem cell injection administered 3 weeks after injury significantly improved both new muscle formation in the area of injury and anal sphincter pressures.

Faecal incontinence: Current knowledges and perspectives

Faecal incontinence (FI) is a disabling and frequent symptom since its prevalence can vary between 5% and 15% of the general population. It has a particular negative impact on quality of life. Many tools are currently available for the treatment of FI, from conservative measures to invasive surgical treatments. The conservative treatment may be dietetic measures, various pharmacological agents, anorectal rehabilitation, posterior tibial nerve stimulation, and transanal irrigation. If needed, patients may have miniinvasive approaches such as sacral nerve modulation or antegrade irrigation. In some cases, a surgical treatment is proposed, mainly external anal sphincter repair. Although these different therapeutic options are available, new techniques are arriving allowing new hopes for the patients. Moreover, most of them are non-invasive such as local application of an α1-adrenoceptor agonist, stem cell injections, rectal injection of botulinum toxin, acupuncture. New more invasive techniques with promising results are also coming such as anal magnetic sphincter and antropylorus transposition. This review reports the main current available treatments of FI and the developing therapeutics tools.

Implantation of autologous muscle-derived stem cells in treatment of fecal incontinence: results of an experimental pilot study

Background

The aim of this study is to present results of the implantation of autologous myoblasts into the external anal sphincter (EAS) in ten patients with fecal incontinence.

Methods

After anatomical and functional assessment of the patients’ EAS, a vastus lateralis muscle open biopsy was performed. Stem cells were extracted from the biopsy specimens and cultured in vitro. Cell suspensions were then administered to the EAS. Patients were scheduled for follow-up visits in 6-week intervals. Total follow-up was 12 months.

Results

All biopsy and cell implantation procedures were performed without complications. Nine of the patients completed a full 12-month follow-up. There was subjective improvement in six patients (66.7 %). In manometric examinations 18 weeks after implantation, squeeze anal pressures and high-pressure zone length increased in all patients, with particularly significant sphincter function recovery in five patients (55.6 %). Electromyographic (EMG) examination showed an increase in signal amplitude in all patients, detecting elevated numbers of propagating action potentials. Twelve months after implantation two patients experienced deterioration of continence, which was also reflected in the deterioration of manometric and EMG parameters. The remaining four patients (44.4 %) still described their continence as better than before implantation and retained satisfactory functional examination parameters.

Conclusions

Implantation of autologous myoblasts gives good short-term results not only in a subjective assessment, but also in objective functional tests. It seems that this promising technology can improve the quality of life of patients with fecal incontinence, but further study is required to achieve better and more persistent results.

Growth factor and small molecule influence on urological tissue regeneration utilizing cell seeded scaffolds

Regenerative medicine strategies combine various attributes from multiple disciplines including stem cell biology, chemistry, materials science and medicine. The junction at which these disciplines intersect provides a means to address unmet medical needs in an assortment of pathologies with the goal of creating sustainable, functional replacement tissues. Tissue damage caused by trauma for example, requires rapid responses in order to mitigate further tissue deterioration. Cell/scaffold composites have been utilized to initiate and stabilize regenerative responses in vivo with the hope that functional tissue can be attained. Along with the gross reconfiguration of regenerating tissues, small molecules and growth factors also play a pivotal role in tissue regeneration. Several regenerative studies targeting a variety of urological tissues demonstrate the utility of these small molecules or growth factors in an in vivo setting.

The future of research in female pelvic medicine

Female pelvic medicine and reconstructive surgery (FPMRS) was recently recognized as a subspecialty by the American Board of Medical Specialties (ABMS). FPMRS treats female pelvic disorders (FPD) including pelvic organ prolapse (POP), urinary incontinence (UI), fecal incontinence (FI), lower urinary tract symptoms (LUTS), lower urinary tract infections (UTI), pelvic pain, and female sexual dysfunction (FSD). These conditions affect large numbers of individuals, resulting in significant patient, societal, medical, and financial burdens. Given that treatments utilize both medical and surgical approaches, areas of research in FPD necessarily cover a gamut of topics, ranging from mechanistically driven basic science research to randomized controlled trials. While basic science research is slow to impact clinical care, transformational changes in a field occur through basic investigations. On the other hand, clinical research yields incremental changes to clinical care. Basic research intends to change understanding whereas clinical research intends to change practice. However, the best approach is to incorporate both basic and clinical research into a translational program which makes new discoveries and effects positive changes to clinical practice. This review examines current research in FPD, with focus on translational potential, and ponders the future of FPD research. With a goal of improving the care and outcomes in patients with FPD, a strategic collaboration of stakeholders (patients, advocacy groups, physicians, researchers, professional medical associations, legislators, governmental biomedical research agencies, pharmaceutical companies, and medical device companies) is an absolute requirement in order to generate funding needed for FPD translational research.