Tissue integration of polyacrylamide hydrogel: an experimental study of periurethral, perivesical, and mammary gland tissue in the pig

Comparison of Morbidity and Retreatment After Urethral Bulking or Midurethral Sling at the Time of Pelvic Organ Prolapse Repair

OBJECTIVE

To compare postprocedure retreatment rates for stress incontinence in patients who underwent either midurethral sling or urethral bulking at the time of concomitant repair of pelvic organ prolapse (POP).

METHODS

This was a retrospective cohort study using data from the Premier Healthcare Database. Using Current Procedural Terminology codes, we identified patients who were undergoing POP repair and concomitant urethral bulking or midurethral sling between the years 2001 and 2018. Patients who underwent concomitant nongynecologic surgery, Burch urethropexy, or oncologic surgery, and those who did not undergo concomitant POP and anti-incontinence surgery, were excluded. Additional data collected included patient demographics, hospital characteristics, surgeon volume, and comorbidities. The primary outcome was a repeat anti-incontinence procedure at 2 years, and the secondary outcome was the composite complication rate.

RESULTS

Over the study period, 540 (0.59%) patients underwent urethral bulking, and 91,005 (99.41%) patients underwent midurethral sling. The rate of a second procedure within 2 years was higher for urethral bulking, compared with midurethral sling (9.07% vs 1.11%, P <.001); in the urethral bulking group, 4.81% underwent repeat urethral bulking and 4.81% underwent midurethral sling. In the midurethral sling group, 0.77% underwent repeat midurethral sling and 0.36% underwent urethral bulking. After adjusting for confounders, midurethral sling was associated with a decreased odds of a repeat anti-incontinence procedure at 2 years (adjusted odds ratio 0.11, 95% CI 0.08-0.16). The probability of any complication at 2 years was higher with urethral bulking (23.0% vs 15.0%, P <.001).

CONCLUSION

Urethral bulking at the time of POP repair is associated with a higher rate of repeat procedure and postoperative morbidity up to 2 years after surgery.

Seven-year efficacy and safety outcomes of Bulkamid for the treatment of stress urinary incontinence

AIMS

Bulking agents are a minimally invasive treatment option for women with stress urinary incontinence (SUI) or stress-predominant mixed urinary incontinence (MUI). The aim of this study was to evaluate long-term efficacy and safety following treatment with Bulkamid as a primary procedure for SUI or stress-predominant MUI.

METHODS

This was an Institutional Review Board-approved single-center retrospective study of female patients with SUI or stress-predominant MUI who had undergone injection with Bulkamid since 2005 and had completed 7 years of follow up. The primary endpoint was patient satisfaction measured on a four-point scale as cured, improved, unchanged, or worse. Secondary outcomes included the number of incontinence pads used, International Consultation on Incontinence Questionnaire-Short Form (ICIQ-UI SF) scores, Visual Analog Scale Quality of Life (VAS QoL), reinjection rates, and perioperative and postoperative complications.

RESULTS

A total of 1,200 patients were treated with Bulkamid since 2005 and of these, 388 (32.3%) had completed 7 years of follow-up. A total of 67.1% of the patients reported feeling cured or improved if Bulkamid was a primary procedure, 11.1% reported no change, and 2.3% reported worsening of incontinence. A total of 19.5% of patients received a subsequent other incontinence procedure. The ICIQ-UI SF was reduced by 8.6 points. VAS QoL improved by a mean of 4.3 points. Postoperative complications were transient. Prolonged bladder emptying time was reported in 15.3% of patients and urinary tract infection in 3.5%.

CONCLUSIONS

Bulkamid injections are an effective and safe first-line treatment option for women with SUI or stress-predominant MUI providing durable outcomes at 7 years.

Particulate Versus Non-Particulate Bulking Agents In The Treatment Of Stress Urinary Incontinence

Stress urinary incontinence (SUI) has been treated surgically with the midurethral sling but in recent years, this option has come under scrutiny and the risk-benefit balance continues to be reviewed. The low-risk alternative for women with uncomplicated SUI is the bulking agent, which aims to achieve continence through coaptation of the urethra. Two classes of bulking agents can be identified: those made from solid microparticles in an absorbable liquid or gel carrier (particulate agents) and those comprising a homogenous gel (non-particulates) that resists absorption. Polydimethylsiloxane®, carbon-coated zirconium oxide®, calcium hydroxyapatite® and polyacrylate polyalcohol copolymer® are currently marketed particulate agents. With the exception of calcium hydroxyapatite, the particles are non-degradable. Each agent achieves its long-term bulking effect through reactive changes around the persisting particles while the carrier volume is lost. Bulkamid® is a non-particulate agent with the bulking effect resulting from the volume of gel injected. The lasting network of fine fibers formed by the host tissue anchors the gel in situ. Foreign-body granulomas, erosion and migration/material extrusion and loss of bulk have been observed in connection with the particle-based products. Bulkamid may be mechanistically less liable to these events; however, there are minimal data directly comparing the two types of bulking agent. The question of durability is inevitable based on their differing modes of action.

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

Efficacy of dextranomer hyaluronic acid and polyacrylamide hydrogel in endoscopic treatment of vesicoureteral reflux: A comparative study

INTRODUCTION

Various bulking agents are available for vesicoureteral reflux (VUR) endoscopic treatment, but their inconsistent success rates and costs are concerns for urologists. Recently, polyacrylamide hydrogel (PAHG) has been shown to have a good overall success rate, which seems comparable to dextranomer hyaluronic acid (Dx/HA), currently the most popular bulking agent. Our objective was to compare the short-term success rate of PAHG and Dx/HA for VUR endoscopic treatment in children.

METHODS

We performed a prospective non-randomized study using PAHG and Dx/HA to treat VUR grades I to IV in pediatric patients. All patients underwent endoscopic sub-ureteric injection of PAHG or Dx/HA, using the double-HIT technique, followed by a 3-month postoperative renal ultrasound and voiding cystourethrogram. Treatment success was defined as the absence of de novo or worsening hydronephrosis and absence of VUR.

RESULTS

A total of 90 pediatric patients underwent an endoscopic injection: 45 patients (78 ureters) with PAHG and 45 patients (71 ureters) with Dx/HA. The mean injected volume of PAHG and Dx/HA was 1.1 mL and 1.0 mL, respectively. The overall success rate 3 months after a single treatment was 73.1% for PAHG and 77.5% for Dx/HA. Postoperatively, 1 patient in each group presented with acute pyelonephritis and 2 patients in the Dx/HA group developed symptomatic ureteral obstruction.

CONCLUSION

Success rates of PAGH and Dx/HA in endoscopic injections for VUR treatment were comparable. The rate of resolution obtained with Dx/HA was equivalent to those previously published. The lower cost of PAHG makes it an interesting option.

An international multi-centre prospective study on the efficacy of an intraarticular polyacrylamide hydrogel in horses with osteoarthritis: a 24 months follow-up

BACKGROUND

Polyacrylamide hydrogel (PAAG) was evaluated recently to treat osteoarthritis (OA) in horses with highly encouraging results; however no long term field-study was done to explore its clinical efficacy and lasting effect. The objective of this study was to evaluate the efficacy of PAAG in improving clinical signs of OA in horses. We hypothesized that lameness grade would significantly improve and the effect would last at least 2 years in osteoarthritic joints treated with PAAG. Forty three horses older than 2 years with OA in only one joint based on clinical evaluation, intra-articular anaesthesia and imaging (radiography) were included in this study. Horses were injected with 2 ml of PAAG into the affected joint and were followed up at 1, 3, 6, 12 and 24 months. Efficacy of PAAG was evaluated by blinded clinical assessment of lameness. Adverse reactions to joint injection were assessed. Data relating to case details, type of activity, joint and limb involved, lameness duration, lameness grading, previous joint treatment, joint effusion grading, radiographic grading, and owner assessment were recorded. Factors associated with the outcome measure "lameness grading" were analyzed using generalized linear mixed model for logistic regression.

RESULTS

At 1, 3, 6, 12 and 24 months follow-up, 59%, 69%, 79%, 81/% and 82.5% of horses were non-lame respectively. Reduction of joint effusion was observed over time. No side effect was observed in the treated joints. There was a significant decrease in lameness grade from baseline to 1, 3, 6, 12 and 24 months (P < 0.0001) and a significant positive association with joint effusion (P < 0.0001). Estimates for odds ratio (OR) showed that the effect of treatment increased over time (OR for lower lameness from month 1 to month 24 relative to baseline increased from 20 to 58).

CONCLUSIONS

PAAG significantly alleviated lameness and joint effusion in osteoarthritic joints. PAAG is a safe and lasting (at least 24 months) OA treatment in horses. PAAG is a promising new treatment for OA in horses.

Long-term follow-up after urethral injection with polyacrylamide hydrogel for female stress incontinence

Urethral injection therapy for treatment of stress urinary incontinence has been in use for years, but only a few long-term follow-up studies have been published. Twenty-five women, injected with polyacrylamide hydrogel 8 years earlier, were invited for follow-up. Twenty-four could be contacted; 15 had had no further treatment, seven had been re-operated with placement of mid-urethral slings, and two had been re-injected with polyacrylamide hydrogel. Eleven women attended for objective examination; all non-attenders were interviewed by telephone. Subjectively, in 44% the stress incontinence was cured or much improved, with a positive outcome according to the King's Health Questionnaire. Objectively, all patients had visible polyacrylamide hydrogel deposits on vaginal ultrasonography. No local adverse reactions were seen in the vaginal mucosa. The results of a later mid-urethral sling were unaffected by previous polyacrylamide hydrogel injection.

Prospective study using a new bulking agent for the treatment of vesicoureteral reflux: polyacrylamide hydrogel

PURPOSE

Vesicoureteral reflux is frequently diagnosed in the pediatric population. Endoscopic treatment has become a popular form of first-line therapy. Available products offer good short-term success rates. However, the cost of these injected implants is an issue. We evaluated the success of endoscopic treatment for vesicoureteral reflux using polyacrylamide hydrogel.

MATERIALS AND METHODS

We performed a single center, single surgeon, prospective, off-label study using polyacrylamide hydrogel to treat vesicoureteral reflux. All patients underwent endoscopic subureteral double hydrodistention implantation technique injection followed by renal ultrasound and voiding cystourethrogram at 3 months postoperatively to confirm the absence of de novo hydronephrosis and correction of vesicoureteral reflux (grade 0).

RESULTS

A total of 40 patients (69 refluxing ureters) underwent polyacrylamide hydrogel injection. Median age at surgery was 50 months. Bilateral reflux was identified in 29 patients (73%). Nine patients had duplex systems, 2 with reflux into both moieties. Reflux was graded using the International Reflux Study in Children grading system, with grade I seen in 9 ureters, II in 17, III in 20, IV in 18 and V in 5. Mean volume injected was 1.1 ml. Success rate for grade I to III vesicoureteral reflux at 3 months after a single treatment was 87%, and the overall success for all grades was 81.2%.

CONCLUSIONS

Off-label use of polyacrylamide hydrogel injection therapy for primarily low grade vesicoureteral reflux demonstrates that the technique and short-term success rates are comparable to the most popular bulking agent, dextranomer/hyaluronic acid. These results suggest that further trials comparing polyacrylamide hydrogel and dextranomer/hyaluronic acid would be worthwhile.

Two-year follow-up of an open-label multicenter study of polyacrylamide hydrogel (Bulkamid®) for female stress and stress-predominant mixed incontinence

INTRODUCTION AND HYPOTHESIS

Polyacrylamide hydrogel (PAHG, Bulkamid®) is a promising urethral bulking agent. This article presents the 2-year follow-up results of a multicenter study of PAHG injections for treating stress and stress-predominant mixed urinary incontinence.

METHODS

Submucosal injection of PAHG was performed in 135 women with urinary incontinence, with subjective and objective assessment of the efficacy and safety 24 months postinjection.

RESULTS

At 24 months, the subjective responder rate was 64 % (a statistically non-significant reduction from 67 % at 12 months). The decreased number of incontinence episodes and urine leakage were maintained compared with the result from the 12-month evaluations, as were objective result rates and quality of life data. No safety issues occurred.

CONCLUSIONS

PAHG is an effective and safe treatment option for women with stress-predominant mixed urinary incontinence, with maintained medium-term responder rates.

Cellular basis of tissue regeneration by omentum

The omentum is a sheet-like tissue attached to the greater curvature of the stomach and contains secondary lymphoid organs called milky spots. The omentum has been used for its healing potential for over 100 years by transposing the omental pedicle to injured organs (omental transposition), but the mechanism by which omentum helps the healing process of damaged tissues is not well understood. Omental transposition promotes expansion of pancreatic islets, hepatocytes, embryonic kidney, and neurons. Omental cells (OCs) can be activated by foreign bodies in vivo. Once activated, they become a rich source for growth factors and express pluripotent stem cell markers. Moreover, OCs become engrafted in injured tissues suggesting that they might function as stem cells.

Omentum consists of a variety of phenotypically and functionally distinctive cells. To understand the mechanism of tissue repair support by the omentum in more detail, we analyzed the cell subsets derived from the omentum on immune and inflammatory responses. Our data demonstrate that the omentum contains at least two groups of cells that support tissue repair, immunomodulatory myeloid derived suppressor cells and omnipotent stem cells that are indistinguishable from mesenchymal stem cells. Based on these data, we propose that the omentum is a designated organ for tissue repair and healing in response to foreign invasion and tissue damage.

Polyacrylamide gel treatment of antiretroviral therapy-induced facial lipoatrophy in HIV patients

BACKGROUND

Today, highly active antiretroviral therapy is lifesaving for most HIV-infected patients, but the treatment can result in facial lipoatrophy, which changes the face so radically that patients may develop severe psychological and social problems. Since 2001 polyacrylamide gel (PAAG) has been used successfully in HIV patients abroad. This article describes the results of a Danish study.

METHODS

Forty HIV patients recruited from two major referral hospitals in the capitol area of Copenhagen, Denmark, each received a series of PAAG gel injections (small deposits in several sessions) with a 14-day interval. Patient satisfaction, injector's evaluation, evaluation by an external specialist in plastic surgery, and long-term aesthetic effect and complications were registered with follow-up until 2 years.

RESULTS

All patients were very satisfied or satisfied with the result. The injector found the result very satisfying in 33 cases and a slight irregularity in 7. The external specialist found improvement in all cases with a one-grade reduction of the lipoatrophy in 11 cases, a two-grade reduction in 20, and a three-grade reduction in 3 cases. No filler-associated complications were recorded.

CONCLUSION

This study has shown that PAAG can normalize contours in patients suffering from facial lipoatrophy within 3-6 sessions, with a mean amount of gel per session of 1.8 ml and a mean total amount of 8.8 ml. The results are in accordance with those of other large studies, confirming a high degree of biocompatibility and safety.

An open multicenter study of polyacrylamide hydrogel (Bulkamid®) for female stress and mixed urinary incontinence

Introduction

Polyacrylamide hydrogel (PAHG, Bulkamid®) is a promising urethral bulking agent. This multicenter study was carried out to evaluate safety and efficacy of Bulkamid® for female stress and mixed urinary incontinence.

Methods

Submucosal injection of Bulkamid® was performed in 135 women with urinary incontinence (stress, 67; mixed, 68) followed for 12 months. Forty-seven had a reinjection (35%).

Results

At 12 months, the subjective response rate was 66%. Incontinence episodes/24 h and urine leakage g/24 h decreased significantly (from 3.0 to 0.7 and 29 g to 4 g, respectively). Additionally, the median International Consultation on Incontinence Questionnaire score was reduced to approximately 50%, and the overall quality of life visual analogue scale score was decreased significantly (from 72 to 20). Efficacy was very similar between patients with stress and mixed incontinence. Thirty treatment-related adverse events were registered. The most frequent was urinary tract infection (n = 10). No polyacrylamide hydrogel-specific adverse events were seen.

Conclusions

Bulkamid® is an effective and safe bulking agent in women with stress or mixed incontinence.