Consequences of adjusting cell density and feed frequency on serum-free expansion of thymic regulatory T cells

Impacts of transient exposure of human T cells to low oxygen, temperature, pH and nutrient levels relevant to bioprocessing for cell therapy applications

BACKGROUND

T-cell therapy advances have stimulated the development of bioprocesses to address the specialized needs of cell therapy manufacturing. During concentrated cell washing, the cells are frequently exposed to transiently reduced oxygen, temperature, pH, and nutrient levels. Longer durations of these conditions can be caused by process deviations or, if they are not harmful, be used to ease the scheduling of process stages during experiments as well as manufacturing.

METHODS

To avoid unpredictable impacts on T-cell quality during bioprocessing, we measured the influences of such environmental exposures generated by settling 250 million activated human T cells per mL, for up to 6 h at temperatures from 4 to 37°C.

RESULTS

The measured glucose concentration decreased to as low as 0.5 mM and the pH to 6, while lactate increased up to 55 mM. The concentrated cell conditions at 37°C resulted in by far the greatest losses in viable cell numbers with, on average, only 58% and 41% of the cells recovered after 3 and 6 h, respectively. Likewise, their subsequent cell expansion cultures were substantially reduced even after only 3 h of exposure, and with decreased percentages of central memory T cells and increased percentages of effector memory and effector T cells. Although under similar environmental conditions at room temperatures, the negative impacts of high cell concentrations were greatly diminished for up to 3 h. At 4°C the transient conditions were less extreme, and the cells well maintained for 6 h.

CONCLUSIONS

Overall, when developing processes and devices for T-cell therapy manufacturing that involve concentrated cells, the results of this study indicate that more practically feasible room temperatures can be used for up to 3 h to obtain high viable cell recoveries whereas lower temperatures such as 4°C should be used if there is a need for more prolonged concentrated T-cell conditions.

Adipose stromal cells increase insulin sensitivity and decrease liver gluconeogenesis in a mouse model of type 1 diabetes mellitus

BACKGROUND

Diabetic ketoacidosis (DKA) is a serious complication of hyperglycemic emergency caused by insulin deficiency through accelerated liver gluconeogenesis and glycogenolysis. DKA is most common in type 1 diabetes (T1D). Transplantation of islet cells and pancreas is an alternative to insulin injection for treating T1D. However, this alternative is only suitable for some patients. This study investigated the effects and mechanisms of adipose stromal vascular fraction (SVF) cells on liver gluconeogenesis and insulin sensitivity in an insulin-dependent T1D animal model.

METHODS

SVF cells were obtained from wild-type inguinal adipose tissue and transplanted into the peritoneal cavity of type I diabetic Akita (Ins2Akita) mice.

RESULTS

We found that transplantation of 5 × 106 SVF cells from wild-type adipose tissue significantly downregulated proinflammatory genes of TNF-α, IL-1β, IL-33, iNOS, and DPP4 in the liver and upregulated anti-inflammatory factors IL-10 and FOXP3 in blood serum and liver tissue 7 days after injection. Moreover, we found that the expression levels of G6pc and Pck1 were significantly decreased in the Akita mice livers. Furthermore, the intraperitoneal insulin tolerance test assay showed that diabetic Akita mice significantly had increased insulin sensitivity, reduced fasting blood glucose, and restored glucose-responsive C-peptide expression compared with the control Akita group. This result was noted 14 days after administration of 5 × 106 or 1 × 107 SVF cells from wild-type adipose tissue into diabetic Akita mice.

CONCLUSIONS

Together, these findings suggest that adipose tissue-derived SVF cells could suppress liver inflammation, regulate liver gluconeogenesis, and improve insulin sensitivity in an animal model with T1D. Therefore, adipose SVF cells may be novel cellular therapeutic alternatives to maintain steady liver gluconeogenesis in T1D.

Harnessing the biology of regulatory T cells to treat disease

Regulatory T (Treg) cells are a suppressive subset of CD4+ T cells that maintain immune homeostasis and restrain inflammation. Three decades after their discovery, the promise of strategies to harness Treg cells for therapy has never been stronger. Multiple clinical trials seeking to enhance endogenous Treg cells or deliver them as a cell-based therapy have been performed and hint at signs of success, as well as to important limitations and unanswered questions. Strategies to deplete Treg cells in cancer are also in active clinical testing. Furthermore, multi-dimensional methods to interrogate the biology of Treg cells are leading to a refined understanding of Treg cell biology and new approaches to harness tissue-specific functions for therapy. A new generation of Treg cell clinical trials is now being fuelled by advances in nanomedicine and synthetic biology, seeking more precise ways to tailor Treg cell function. This Review will discuss recent advances in our understanding of human Treg cell biology, with a focus on mechanisms of action and strategies to assess outcomes of Treg cell-targeted therapies. It highlights results from recent clinical trials aiming to enhance or inhibit Treg cell activity in a variety of diseases, including allergy, transplantation, autoimmunity and cancer, and discusses ongoing strategies to refine these approaches.

Sex-biased human thymic architecture guides T cell development through spatially defined niches

Within the thymus, regulation of the cellular crosstalk directing T cell development depends on spatial interactions within specialized niches. To create a spatially defined map of tissue niches guiding human postnatal T cell development, we employed the multidimensional imaging platform co-detection by indexing (CODEX) as well as cellular indexing of transcriptomes and epitopes sequencing (CITE-seq) and assay for transposase accessible chromatin sequencing (ATAC-seq). We generated age-matched 4- to 5-month-old human postnatal thymus datasets for male and female donors, identifying significant sex differences in both T cell and thymus biology. We demonstrate a possible role for JAG ligands in directing thymic-like dendritic cell development, identify important functions of a population of extracellular matrix (ECM)- fibroblasts, and characterize the medullary niches surrounding Hassall's corpuscles. Together, these data represent an age-matched spatial multiomic resource to investigate how sex-based differences in thymus regulation and T cell development arise, providing an essential resource to understand the mechanisms underlying immune function and dysfunction in males and females.

A phase 2 randomized trial with autologous polyclonal expanded regulatory T cells in children with new-onset type 1 diabetes

CD4+CD25hiCD127lo/-FOXP3+ regulatory T cells (Tregs) play a key role in preventing autoimmunity. In autoimmune type 1 diabetes (T1D), adoptive transfer of autologous polyclonal Tregs has been shown to be safe in adults in phase 1 clinical trials. We explored factors contributing to efficacy of autologous polyclonal expanded Tregs (expTregs) in a randomized phase 2 multi-center, double-blind, clinical trial (Sanford/Lisata Therapeutics T-Rex phase 2 trial, ClinicalTrials.gov NCT02691247). One hundred ten treated children and adolescents with new-onset T1D were randomized 1:1:1 to high-dose (20 × 106 cells/kilogram) or low-dose (1 × 106 cells/kilogram) treatments or to matching placebo. Cytometry as well as bulk and single-cell RNA sequencing were performed on selected expTregs and peripheral blood samples from participants. The single doses of expTregs were safe but did not prevent decline in residual β cell function over 1 year compared to placebo (P = 0.94 low dose, P = 0.21 high dose), regardless of age or baseline C-peptide. ExpTregs were highly activated and suppressive in vitro. A transient increase of activated memory Tregs was detectable 1 week after infusion in the high-dose cohort, suggesting effective transfer of expTregs. However, the in vitro fold expansion of expTregs varied across participants, even when accounting for age, and lower fold expansion and its associated gene signature were linked with better C-peptide preservation regardless of Treg dose. These results suggest that a single dose of polyclonal expTregs does not alter progression in T1D; instead, Treg quality may be an important factor.

Regulatory T-cell dysfunction and its implication for cell therapy

Regulatory T cells (Tregs) are a subtype of CD4+ T cells that can mediate immune tolerance by a multitude of immunomodulatory mechanisms. Treg-based adoptive immunotherapy is currently being tested in multiple phases I and II clinical trials in transplantation and autoimmune diseases. We have learned from the work done on conventional T cells that distinct mechanistic states can define their dysfunctions, such as exhaustion, senescence, and anergy. All three can negatively impact the therapeutic effectiveness of T-cell-based therapies. However, whether Tregs are susceptible to such dysfunctional states is not well studied, and results are sometimes found to be controversial. In addition, Treg instability and loss of FOXP3 expression is another Treg-specific dysfunction that can decreasein their suppressive potential. A better understanding of Treg biology and pathological states will be needed to compare and interpret the results of the different clinical and preclinical trials. We will review herein Tregs' mechanisms of action, describe different T-cell dysfunction subtypes and how and if they apply to Tregs (exhaustion, senescence, anergy, and instability), and finally how this knowledge should be taken into consideration when designing and interpreting Treg adoptive immunotherapy trials.

Sex biased human thymic architecture guides T cell development through spatially defined niches

Within the thymus, regulation of the cellular cross-talk directing T cell development is dependent on spatial interactions within specialized niches. To create a holistic, spatially defined map of tissue niches guiding postnatal T cell development we employed the multidimensional imaging platform CO-detection by indEXing (CODEX), as well as CITE-seq and ATAC-seq. We generated age-matched 4-5-month-old postnatal thymus datasets for male and female donors, and identify significant sex differences in both T cell and thymus biology. We demonstrate a crucial role for JAG ligands in directing thymic-like dendritic cell development, reveal important functions of a novel population of ECM- fibroblasts, and characterize the medullary niches surrounding Hassall's corpuscles. Together, these data represent a unique age-matched spatial multiomic resource to investigate how sex-based differences in thymus regulation and T cell development arise, and provide an essential resource to understand the mechanisms underlying immune function and dysfunction in males and females.

Clinical adoptive regulatory T Cell therapy: State of the art, challenges, and prospective

Rejection of solid organ transplant and graft versus host disease (GvHD) continue to be challenging in post transplantation management. The introduction of calcineurin inhibitors dramatically improved recipients' short-term prognosis. However, long-term clinical outlook remains poor, moreover, the lifelong dependency on these toxic drugs leads to chronic deterioration of graft function, in particular the renal function, infections and de-novo malignancies. These observations led investigators to identify alternative therapeutic options to promote long-term graft survival, which could be used concomitantly, but preferably, replace pharmacologic immunosuppression as standard of care. Adoptive T cell (ATC) therapy has evolved as one of the most promising approaches in regenerative medicine in the recent years. A range of cell types with disparate immunoregulatory and regenerative properties are actively being investigated as potential therapeutic agents for specific transplant rejection, autoimmunity or injury-related indications. A significant body of data from preclinical models pointed to efficacy of cellular therapies. Significantly, early clinical trial observations have confirmed safety and tolerability, and yielded promising data in support of efficacy of the cellular therapeutics. The first class of these therapeutic agents commonly referred to as advanced therapy medicinal products have been approved and are now available for clinical use. Specifically, clinical trials have supported the utility of CD4⁺CD25+FOXP3+ regulatory T cells (Tregs) to minimize unwanted or overshooting immune responses and reduce the level of pharmacological immunosuppression in transplant recipients. Tregs are recognized as the principal orchestrators of maintaining peripheral tolerance, thereby blocking excessive immune responses and prevent autoimmunity. Here, we summarize rationale for the adoptive Treg therapy, challenges in manufacturing and clinical experiences with this novel living drug and outline future perspectives of its use in transplantation.