Prevention of Antidrug Antibody Formation to Infliximab in Crohn's Patients With Prior Failure of Thiopurines.

BACKGROUND & AIMS: Combination thiopurine-infliximab (IFX) therapy is associated with reduced generation of antidrug antibodies (ADA) compared with IFX monotherapy. Whether past clinical response to thiopurine therapy bears an effect on ADA prevention is unknown. METHODS: This was a retrospective observational multicenter study of patients with Crohn's disease (CD) treated by IFX and thiopurines who had serial ADA measurements. Therapy was classified into past thiopurine response or its lack of, de novo combination, or IFX monotherapy. The primary endpoint was risk of ADA appearance. RESULTS: Out of 494 patients with serial ADA measurements 207 eligible patients were included in the final analysis. The 1-year cumulative risk of ADA development was similar in past thiopurine responders (19.3%) compared with past thiopurine failures (16.1%) (log rank P = .54). ADA was found in 46.6% of the monotherapy group and was significantly different compared with past thiopurine responders (P = .007) and past thiopurine failures (P = .007). The adjusted hazards for ADA development were significantly lower in past responders and past failures compared with the monotherapy group (hazard ratio, 0.47 [95% CI, 0.22-1.00] and 0.32 [95% CI, 0.11-0.93], respectively). CONCLUSIONS: Thiopurines-IFX cotherapy in patients with Crohn's disease is associated with reduced ADA formation compared with IFX monotherapy. This is probably regardless of initial thiopurine therapeutic effect.

Evolution of cytokines and inflammatory biomarkers during infliximab induction therapy and the impact of inflammatory burden on primary response in patients with Crohn's disease.

OBJECTIVE: Primary non-response to infliximab in Crohn's disease is still incompletely understood. Our aim was to further characterize the role of inflammatory burden during infliximab induction therapy. MATERIALS AND METHODS: We studied a well-characterized cohort of 201 anti-TNF naive Crohn's disease patients treated with infliximab 5mg/kg at week 0, 2, 6 and 14 who had serum samples drawn just before every infusion. All serum samples were analyzed for CRP, albumin, TNF, IFN-γ, IL-6, IL-8, IL-10, infliximab trough concentrations (in-house-developed ELISA) and antibodies to infliximab (HMSA, Prometheus Laboratories Inc., San Diego, CA). Primary non-response was defined as the absence of clinical improvement at week 14. RESULTS: The incidence of primary non-response to infliximab was 8% (n = 16). IL-8 concentrations at baseline were higher (p = .01) and albumin at week 6 was lower in primary non-responders (p = .01) compared to responders. During induction, IFN-γ and IL-6 concentrations decreased significantly at week 2 and week 6 in responders compared to primary non-responders (p < .05). Serum TNF increased significantly after each infliximab infusion and this increase from week 0 to week 14 was more pronounced in responders (p = .03). Multiple logistic regression identified TNF/CRP ratio at baseline as predictive for primary non-response to infliximab at week 14 (OR 2.8 (95% CI 1.4-5.5; p = .003)). CONCLUSIONS: In this intensively sampled cohort of Crohn's disease patients, we demonstrate that inflammatory burden is more determining for primary non-response than drug exposure or immunogenicity. Our findings furthermore suggest that the contribution of TNF in inflammation might be higher in primary non-response, contradicting the non-TNF-driven concept.

Characteristics of Skin Lesions Associated With Anti-Tumor Necrosis Factor Therapy in Patients With Inflammatory Bowel Disease: A Cohort Study.

BACKGROUND: A subgroup of patients with inflammatory bowel disease (IBD) treated with anti-tumor necrosis factor (TNF) antibodies develop skin lesions, but the lesions and their clinical course are not well-characterized. OBJECTIVE: To describe patients treated with anti-TNF antibodies who did and did not develop skin lesions. DESIGN: Retrospective cohort. SETTING: Single IBD tertiary referral center. PATIENTS: 917 consecutive patients with IBD who initiated anti-TNF therapy. MEASUREMENTS: Skin lesions, patient demographic characteristics, treatments, clinical course, and serologic and genetic markers. RESULTS: During a median follow-up of 3.5 years (interquartile range [IQR], 0.5 to 7.4 years), skin lesions associated with the use of anti-TNF therapy developed in 264 of 917 (29%) patients (psoriasiform eczema, 30.6%; eczema, 23.5%; xerosis cutis, 10.6%; palmoplantar pustulosis, 5.3%; psoriasis, 3.8%; other, 26.1%). Lesions typically developed at flexural regions, genitalia, and the scalp, especially the psoriasiform lesions. Thirty-one percent of women and 26% of men developed lesions. Median cumulative doses (2864 mg/y [IQR, 2203 to 3819 mg/y] and 2927 mg/y [IQR, 2377 to 3667 mg/y]) and trough levels (4.2 µg/mL [IQR, 2.6 to 5.8 µg/mL] and 4.0 µg/mL [IQR, 1.6 to 5.9 µg/mL]) of infliximab were similar in patients with and without lesions. All but 28 patients (11%) were successfully managed without needing to stop therapy because of lesions. LIMITATION: Retrospective nature and no matched control group of patients not receiving anti-TNF therapy. CONCLUSION: Skin lesions occur frequently in association with anti-TNF therapy but rarely require discontinuation of therapy. Close surveillance and early referral to a dedicated dermatologist are recommended. PRIMARY FUNDING SOURCE: Research Foundation Flanders (FWO), Belgium; Geconcerteerde Onderzoekacties of KU Leuven; and Janssen Biologics.

Infliximab Concentration Thresholds During Induction Therapy Are Associated With Short-term Mucosal Healing in Patients With Ulcerative Colitis.

BACKGROUND & AIMS: Mucosal healing is an independent predictor of sustained clinical remission in patients with ulcerative colitis (UC) treated with infliximab. We investigated whether infliximab concentrations during induction therapy are associated with short-term mucosal healing (STMH) in patients with UC. METHODS: We performed a retrospective, single-center analysis of data collected from a tertiary referral center from 101 patients with UC who received scheduled induction therapy with infliximab at weeks 0, 2, and 6 and had an endoscopic evaluation at baseline and after induction therapy. STMH was defined as Mayo endoscopic sub-score ≤1, assessed at weeks 10-14, with baseline sub-score ≥2. Infliximab concentrations were evaluated in serum samples collected at weeks 0, 2, 6, and 14 of infliximab therapy by using an enzyme-linked immunosorbent assay we developed. RESULTS: Fifty-four patients (53.4%) achieved STMH. Patients with STMH had a higher median infliximab concentration at weeks 2, 6, and 14 than patients without STMH. A receiver operating characteristic (ROC) analysis identified infliximab concentration thresholds of 28.3 (area under the ROC curve [AUROC], 0.638), 15 (AUROC, 0.688), and 2.1 µg/mL (AUROC, 0.781) that associated with STMH at weeks 2, 6, and 14, respectively. Multiple logistic regression analysis identified infliximab concentration ≥15 at week 6 (P = .025; odds ratio, 4.6; 95% confidence interval, 1.2-17.1) and ≥2.1 µg/mL at week 14 (P = .004; odds ratio, 5.6; 95% confidence interval, 1.7-18) as independent factors associated with STMH. CONCLUSIONS: In an analysis of data from real-life clinical practice, we associated infliximab concentrations during the induction therapy with STMH in patients with UC.

A Genetic Variation in the Neonatal Fc-Receptor Affects Anti-TNF Drug Concentrations in Inflammatory Bowel Disease.

OBJECTIVES: Ample evidence exists that Anti-tumor necrosis factor (TNF) concentrations during induction determine short and long-term outcome in inflammatory bowel disease (IBD). We investigated if a variable number of tandem repeats (VNTR) polymorphism in the neonatal Fc-receptor (FcRn), responsible for extending half-life of IgG, influences anti-TNF concentrations in patients with IBD. METHODS: Retrospective single-center study, including a cohort of 395 infliximab (IFX) naive IBD patients treated with IFX 5 mg/kg on weeks 0, 2, and 6 and a second cohort of 139 adalimumab naive patients, treated with adalimumab 160-80-40 mg on weeks 0, 2, and 4. Area under the serum anti-TNF concentration-time curve (AUC), from week 2 and 6 for IFX and week 2 and 4 for adalimumab, was used to identify factors influencing these drug concentrations. RESULTS: The VNTR2/VNTR3 genotype was associated with a 14% lower IFX AUC compared with patients homozygous for VNTR3/VNTR3 (P=0.03), although this effect became apparent only when immunogenicity (26% lower concentrations, P=9 × 10-5) was not present. Prior anti-TNF use predicted a 27% lower IFX AUC (P=0.002). Similarly, VNTR2/VNTR3 patients had a 24% predicted lower adalimumab AUC than VNTR3/VNTR3 patients (P=0.005). The combined presence of VNTR2/VNTR3 genotype, male gender, and prior IFX use predicted a 41% lower adalimumab AUC concentration (P=0.04). CONCLUSIONS: The VNTR2/3 genotype in the FcRn gene is associated with lower IFX but also lower adalimumab drug exposure during induction in patients with IBD. Previously identified pharmacokinetic modifying factors were confirmed. Identifying risk factors in patients is important as higher induction doses may be needed to ensure optimal disease outcome.

A panel to predict long-term outcome of infliximab therapy for patients with ulcerative colitis.

BACKGROUND & AIMS: Infliximab is effective for patients with refractory ulcerative colitis (UC), but few factors have been identified that predict long-term outcome of therapy. We aimed to identify a panel of markers associated with outcome of infliximab therapy to help physicians make personalized treatment decisions. METHODS: We collected data from the first 285 patients with refractory UC (41% female; median age, 39 y) treated with infliximab before July 2012 at University Hospitals Leuven, in Belgium. We performed a Cox regression analysis to identify independent factors that predicted relapse-free and colectomy-free survival, and used these factors to create a panel of markers (risk panel). RESULTS: During a median follow-up period of 5 years, 61% of patients relapsed and 20% required colectomy. Independent predictors of relapse-free survival included short-term complete clinical response (odds ratio [OR], 3.75; 95% confidence interval [CI], 2.35-5.97; P < .001), mucosal healing (OR, 1.87; 95% CI, 1.17-2.98; P = .009), and absence of atypical perinuclear antineutrophil cytoplasmic antibodies (pANCA) (OR, 1.96; 95% CI, 1.23-3.12; P = .005). Independent predictors of colectomy-free survival included short-term clinical response (OR, 7.74; 95% CI, 2.76-21.68; P < .001), mucosal healing (OR, 4.02; 95% CI, 1.16-13.97; P = .028), baseline level of C-reactive protein (CRP) of 5 mg/L or less (OR, 2.95; 95% CI, 1.26-6.89; P = .012), and baseline level of albumin of 35 g/L or greater (OR, 3.03; 95% CI, 1.12-8.22; P = .029). Based on serologic analysis of a subgroup of 112 patients, levels of infliximab greater than 2.5 µg/mL at week 14 of treatment predicted relapse-free survival (P < .001) and colectomy-free survival (P = .034). A risk panel that included levels of pANCA, CRP, albumin, clinical response, and mucosal healing identified patients at risk for UC relapse or colectomy (both P < .001). CONCLUSIONS: Clinical response and mucosal healing were confirmed as independent predictors of long-term outcome from infliximab therapy in patients with UC. We identified additional factors (levels of pANCA, CRP, and albumin) to create a risk panel that predicts long-term outcomes of therapy. Serum levels of infliximab at week 14 of treatment also were associated with patient outcomes. Our risk panel and short-term serum levels of infliximab therefore might be used to guide therapy.

The use of prognostic factors in inflammatory bowel diseases.

The disease spectrum and natural course of Crohn's disease and ulcerative colitis are highly variable. The majority of Crohn's disease patients will require surgery at a certain stage in their disease compared to only a fraction of the ulcerative colitis patients. Similarly, some patients are destined to experience an indolent disease course while others will require early intensive therapy. Ideally, these subtypes of patients should be identified as early as possible with the help of reliable prognostic factors in order to guide personalized therapeutic decisions. In this review, the authors focused on the most relevant reports on the use of different prognostic factors to predict disease course, postoperative recurrence and response to therapy in patients with inflammatory bowel disease. The last 15 years have seen a wealth of novel genetic and serological markers of disease severity. Nevertheless, none of these markers have proven to be superior to careful clinical phenotyping and endoscopic features early in the disease course. Future attempts should apply an integrated approach that unites clinical, serological and (epi)genetic information with environmental influences, with a clear focus on the microbiome to ultimately identify molecular-based and clinically relevant subgroups.

The operative risk and natural history after the diagnosis of ileal penetrating Crohn's disease.

BACKGROUND AND PURPOSE: Crohn's disease (CD) is marked by transmural inflammation of the bowel wall leading to stricturing and/or penetrating complications in the majority of patients. The natural history and operative risk after the diagnosis of an ileal penetrating complication is understudied. The aim was to study the disease course and need for surgery in patients diagnosed with a penetrating ileal CD complication and to assess the risk factors associated with worse postoperative outcome. PATIENTS AND METHODS: In this cohort study, all cross-sectional imaging exams (computed tomography and/or magnetic resonance imaging) performed between 2006 and 2014 in patients with CD in a tertiary referral centre were reviewed for the presence of ileal penetrating complications (defined as abscesses, phlegmones and/or fistula). Demographic, clinical, biochemical, radiological and endoscopic factors were assessed retrospectively in these patients as well as the need for surgery (intestinal resection and/or strictureplasties) and postoperative complications. RESULTS: In total, 1803 cross-sectional imaging exams in 957 CD patients were performed during the study period. In 113 patients, penetrating ileal CD complications were identified. The majority of these patients were referred for surgery (86%) (median time to surgery 1 month, interquartile range: 1-4.9 months). In multivariate analysis, only the presence of abscesses was associated with subsequent surgery (P=0.034; hazard ratio=1.65; 95% confidence interval: 1.04-2.61). Severe postoperative complications (Dindo-Clavien>II) were present in 13% of the patients. Albumin less than 32 g/l was associated with a five-fold increase in severe complications (P=0.039; hazard ratio=4.9; 95% confidence interval: 1-22). Up to 35% of the patients needed no further medical treatment during the first 5 years postoperatively. CONCLUSION: In this cohort, the majority of patients with penetrating ileal CD underwent surgery. The presence of an abscess showed a significant association with the need for surgery. There was an acceptable postoperative complication rate. Patients with low albumin had an unfavourable postoperative course. The long-term outcome after surgery was favourable.

Risk Stratification for Surgery in Stricturing Ileal Crohn's Disease: The BACARDI Risk Model.

BACKGROUND AND AIM: Transmural inflammation in Crohn's disease [CD] leads to stricturing or penetrating complications. Factors impacting on the need and timing of surgery in ileal stricturing CD [IS-CD] are understudied. Our aim was to identify risk factors in IS-CD associated with the need for surgery over time. METHODS: All cross-sectional imaging [XSI] performed for CD between 2006 and 2015 in a tertiary referral centre was analysed. The electronic charts of patients with IS-CD were reviewed for demographic, clinical, biochemical, imaging, genetic, and endoscopic factors. An independent cohort was used for validation. RESULTS: A total of 1803 XSI were performed in 957 patients with CD. IS-CD was diagnosed in 235 patients, and 161 of these [69%] needed surgery. Prestenotic dilation (hazard ratio [HR] 2.05, 95% confidence interval [CI] 1.22-3.45, p = 0.007], C-reactive protein at diagnosis of IS-CD > 11 mg/L [HR 1.53, 95% CI 1.05-2.24, p = 0.026], Montreal B3 phenotype [HR 1.58, 95% CI 1.06-2.36, p = 0.023], previous/current anti-tumour necrosis factor [TNF] exposure [HR 1.44, 95% CI 1.00-2.06, p = 0.048], and presence of at least one NOD2 rs2066844 risk allele [HR 1.51, 95% CI 1.02-2.23, p = 0.038] significantly impacted on the need for surgery in multivariate analysis. The risk stratification model [BACARDI] yielded a surgery-free survival after 5 years of 77%, 38%,19%, and 0% for the low, medium, high, and all risk groups, respectively. Based on an independent cohort of 27 patients, the results were validated and demonstrated adequate performance. CONCLUSIONS: This risk model can facilitate therapeutic decisions in IS-CD and suggest the correct time for surgery in daily clinical practice.

Incidence of renal cell carcinoma in inflammatory bowel disease patients with and without anti-TNF treatment.

OBJECTIVE: We aimed to study the risk of renal cell carcinoma (RCC) with anti-tumor necrosis factor (anti-TNF) therapy in inflammatory bowel disease (IBD) and rheumatic diseases (RD) and calculate standardized incidence ratios (SIRs) in IBD. MATERIALS AND METHODS: This was a retrospective case-control and cohort study spanning 25 years, including IBD and RD patients with a diagnosis of RCC (1990-2014) identified through the electronic database of a tertiary referral center. RESULTS: RCC was confirmed in seven anti-TNF-exposed (TNF+) and 21 anti-TNF-naive (TNF-) IBD and one TNF+ and 26 TNF- RD patients. In IBD-RCC, younger age at RCC diagnosis [median (interquartile range) 46 (42-58) vs. 63 (52-75) years; P=0.02], immunosuppressive therapy (100 vs. 24%; P<0.0004), partial nephrectomy (86 vs. 33%; P=0.02), and surgery less than 1 month after diagnosis of RCC (71 vs. 14%; P=0.004) were associated with anti-TNF. Compared with IBD, RD patients were older at RCC diagnosis [70 (60-77) vs. 59 (47-69) years; P=0.02] with less nephron-sparing surgery (26 vs. 54%; P=0.04) and more symptomatic (44 vs. 14%; P=0.02) and advanced tumors (30 vs. 7%; P=0.04). SIRs in IBD-RCC TNF- and TNF+ were 5.4 (95% confidence interval 2.9-9.2) and 7.1 (2.3-16.5) in male patients and 8.5 (3.7-16.8) and 4.8 (0.6-17.3) in female patients, respectively. The risk for RCC associated with anti-TNF in IBD was 0.8 (0.3-2.5) in men and 1.4 (0.2-5.5) in women. CONCLUSION: The favorable patient and tumor profiles in IBD with anti-TNF may suggest incidentally discovered RCC on abdominal imaging. SIRs for IBD-RCC were not increased after anti-TNF exposure.

Long-Term Outcome of Patients with Ulcerative Colitis and Primary Non-response to Infliximab.

BACKGROUND AND AIMS: We studied the long-term outcome of patients with ulcerative colitis [UC] and primary non response [PNR] to infliximab and searched for predictors of colectomy in these patients. METHODS: This retrospective, multi-centre study included UC patients from three European referral centres, with PNR to infliximab defined as a lack of clinical improvement after the induction therapy, leading to drug discontinuation. Relapse, for patients who continued on biologicals after PNR to infliximab, was defined as drug discontinuation for PNR, loss of response, or serious adverse event. Serum infliximab concentrations at Weeks 2 and 6 were evaluated using an enzyme-linked immunosorbent assay [ELISA] developed in house. RESULTS: The study population consisted of 99 anti-tumour necrosis factor [TNF]-naïve patients with UC and PNR to infliximab. At the end of follow-up (median: 3.2 [interquartile range 1-6.3] years), 55 [55.6%] of these patients underwent colectomy. Multiple Cox regression analysis identified acute severe UC (hazard ratio [HR]: 24; 95% confidence interval [CI]: 2.5-231; p = 0.006], baseline C-reactive protein [CRP] > 5mg/l [HR: 11; 95% CI: 2.1-58.8; p = 0.005], baseline albumin < 40g/l [HR: 9.5; 95% CI: 1.3-71.4; p = 0.026], and infliximab concentration at Week 2 < 16.5 µg/ml [HR: 5.6; 95% CI: 1.1-27.8; p = 0.034] as independent predictors of colectomy. Regarding patients who continued on biologicals after PNR to infliximab, there was a marginally higher cumulative probability for relapse in patients switching to another anti-TNF agent compared with those swapping to vedolizumab [p logrank = 0.08]. CONCLUSIONS: About half of UC patients with PNR to infliximab will undergo colectomy. Patients with severe inflammation and low serum infliximab concetrations during the induction phase are at greatest risk.

Differences between adults and children: genetics and beyond.

Clinical observations and epidemiological studies have highlighted some important differences in disease course and phenotypes between pediatric inflammatory bowel disease (IBD) and adult-onset IBD. Also from a therapeutic angle, the approach to young-onset IBD is different with a more rapid introduction of azathioprine and a high threshold for long and systemic steroid use, which may affect bone mineral density and growth. The observed clinical differences have been an area of scientific research and genetic studies have been the focus of attention. Specific candidate gene studies as well as genome-wide association studies have been performed in pediatric IBD. With the exception of very early-onset IBD occurring before the age of 2 years; no overt differences in genetic susceptibility have been identified. In contrast, very early-onset IBD seems in particular to be a genetic disease with defects in the IL10 signaling pathway being the principal example. This review aims to answer some straightforward questions arising in this topic by giving concise information.

An Optimized Anti-infliximab Bridging Enzyme-linked Immunosorbent Assay for Harmonization of Anti-infliximab Antibody Titers in Patients with Inflammatory Bowel Diseases.

BACKGROUND: The formation of anti-infliximab antibodies (ATI) is associated with loss of response and adverse events in patients with inflammatory bowel diseases, leading to the introduction of ATI monitoring for guiding treatment adjustments. However, a lack of standardization among current available assays exists, hampering comparison of results from different studies. This study aimed to improve the harmonization of clinically validated ATI enzyme-linked immunosorbent assays (ELISAs) by introducing a monoclonal anti-infliximab antibody (MA-IFX). METHODS: A panel of MA-IFX was evaluated as calibrator in the first generation ATI ELISA. After selection of 1 MA-IFX, assay conditions were optimized and biotin-streptavidin-enhanced detection of bound infliximab was introduced. The novel second generation ELISA was used for reanalysis of 127 serum samples from a cohort of 12 patients with inflammatory bowel disease, previously identified as ATI positive. RESULTS: Of 55 MA-IFX, MA-IFX10F9 was selected as calibrator in the ATI ELISA. After optimization of the assay conditions, a 4-fold improvement in sensitivity was obtained. Reanalysis of 127 serum samples revealed that in 5 of 12 patients (46%), ATI were detected at least 1 time point earlier with the second generation ELISA compared with the first generation ELISA. In 1 patient, the second generation ELISA allowed to detect ATI before the reinitiation of IFX after a drug holiday. CONCLUSIONS: In addition to the improved sensitivity and specificity of the second generation ATI ELISA, MA-IFX10F9 can serve as a universal calibrator to achieve assay harmonization. Moreover, the superiority of the second generation assay in analyzing serum of restarters was demonstrated.

A Matrix-based Model Predicts Primary Response to Infliximab in Crohn's Disease.

BACKGROUND: Prediction of primary non-response [PNR] to anti-tumour necrosis factors [TNFs] in inflammatory bowel disease [IBD] is direly needed to select the optimal therapeutic class for a given patient. We developed a matrix-based prediction tool to predict response to infliximab [IFX] in Crohn's disease [CD] patients. METHODS: This retrospective single-centre study included 201 anti-TNF naïve CD patients who started with IFX induction therapy. PNR occurred in 16 [8%] patients. Clinical, biological [including serum TNF and the IBD serology 6 panel and genetic [the 163 validated IBD risk loci] markers were collected before start. Based on the best fitted regression model, probabilities of primary response to IFX were calculated and arranged in a prediction matrix tool. RESULTS: Multiple logistic regression withheld three final independent predictors [p < 0.05] for PNR: age at first IFX, {odds ratio (OR) (95% confidence interval [CI] of 1.1 (1.0-1.1)}, body mass index [BMI] (0.86 [0.7-1.0]), and previous surgery (4.4 [1.2-16.5]). The accuracy of this prediction model did not improve when the genetic markers were added (area under the curve [AUC] from 0.80 [0.67-0.93] to 0.78 [0.65-0.91]). The predicted probabilities for PNR to IFX increased from 1% to 53% depending on the combination of final predictors. CONCLUSIONS: Readily available clinical factors [age at first IFX, BMI, and previous surgery] outperform serological and IBD risk loci in prediction of primary response to infliximab in this real-life cohort of CD patients. This matrix tool could be useful for guiding physicians and may avoid unnecessary or inappropriate exposure to IFX in IBD patients unlikely to benefit.

Galactose-functionalized gelatin hydrogels improve the functionality of encapsulated HepG2 cells.

The present study investigates the effect of galactosylated gelatin on encapsulated HepG2 cells. Methacrylamide modified gelatin is evaluated and compared with its galactosylated counterpart with respect to effects on viability, morphological characteristics, proliferation, and the expression of hepatocyte specific markers. The research reveals that further modifications of methacrylamide modified gelatin are possible without affecting the survival of the encapsulated cells (viability of 90%). Moreover, the study demonstrates a clear and long-term (up to 21 d) improvement in hepatocyte specific gene expression when the cells are encapsulated in the galactosylated gelatin. It is concluded that the use of galactosylated gelatin derivates supports the hepatocyte phenotype.

The 3D printing of gelatin methacrylamide cell-laden tissue-engineered constructs with high cell viability.

In the present study, we report on the combined efforts of material chemistry, engineering and biology as a systemic approach for the fabrication of high viability 3D printed macroporous gelatin methacrylamide constructs. First, we propose the use and optimization of VA-086 as a photo-initiator with enhanced biocompatibility compared to the conventional Irgacure 2959. Second, a parametric study on the printing of gelatins was performed in order to characterize and compare construct architectures. Hereby, the influence of the hydrogel building block concentration, the printing temperature, the printing pressure, the printing speed, and the cell density were analyzed in depth. As a result, scaffolds could be designed having a 100% interconnected pore network in the gelatin concentration range of 10-20 w/v%. In the last part, the fabrication of cell-laden scaffolds was studied, whereby the application for tissue engineering was tested by encapsulation of the hepatocarcinoma cell line (HepG2). Printing pressure and needle shape was revealed to impact the overall cell viability. Mechanically stable cell-laden gelatin methacrylamide scaffolds with high cell viability (>97%) could be printed.