Comparison of 3 biodegradable polymer and durable polymer-based drug-eluting stents in all-comers (BIO-RESORT): rationale and study design of the randomized TWENTE III multicenter trial

One-Month Dual Antiplatelet Therapy Followed by P2Y12 Inhibitor Monotherapy After Biodegradable Polymer Drug-Eluting Stent Implantation - The REIWA Region-Wide Registry

BACKGROUND

The safety and feasibility of using 1-month dual antiplatelet therapy (DAPT) followed by P2Y12inhibitor monotherapy for patients after percutaneous coronary intervention (PCI) with thin-strut biodegradable polymer drug-eluting stents (BP-DES) in daily clinical practice remain uncertain.

METHODS AND RESULTS

The REIWA region-wide registry is a prospective study conducted in 1 PCI center and 9 local hospitals in northern Japan. A total of 1,202 patients who successfully underwent final PCI using BP-DES (Synergy: n=400; Ultimaster: n=401; Orsiro: n=401), were enrolled in the registry, and received 1-month DAPT followed by P2Y12inhibitor (prasugrel 3.75 mg/day or clopidogrel 75 mg/day) monotherapy. The primary endpoint was a composite of cardiovascular and bleeding events at 12 months, including cardiovascular death, myocardial infarction (MI), definite stent thrombosis (ST), ischemic or hemorrhagic stroke, and Thrombolysis in Myocardial Infarction (TIMI) major or minor bleeding. Based on the results of a previous study, we set the performance goal at 5.0%. Over the 1-year follow-up, the primary endpoint occurred in 3.08% of patients, which was lower than the predefined performance goal (Pnon-inferiority<0.0001). Notably, definite ST occurred in only 1 patient (0.08%) within 1 year (at 258 days). No differences were observed in the primary endpoint between stent types.

CONCLUSIONS

The REIWA region-wide registry suggests that 1-month DAPT followed by P2Y12inhibitor monotherapy is safe and feasible for Japanese patients with BP-DES.

Safety of 3-Month Dual Antiplatelet Therapy After Implantation of Ultrathin Sirolimus-Eluting Stents With Biodegradable Polymer (Orsiro): Results From the SMART-CHOICE Trial

Background

This study sought to investigate the safety of 3‐month dual antiplatelet therapy (DAPT) in patients receiving ultrathin sirolimus‐eluting stents with biodegradable polymer (Orsiro).

Methods and Results

The SMART‐CHOICE (Smart Angioplasty Research Team: Comparison Between P2Y12 Antagonist Monotherapy vs Dual Anti‐ platelet Therapy in Patients Undergoing Implantation of Coronary Drug‐Eluting Stents) randomized trial compared 3‐month DAPT followed by P2Y12 inhibitor monotherapy with 12‐month DAPT in 2993 patients undergoing percutaneous coronary intervention. The present analysis was a prespecified subgroup analysis for patients receiving Orsiro stents. As a post hoc analysis, comparisons between Orsiro and everolimus‐eluting stents were also done among patients receiving 3‐month DAPT. Of 972 patients receiving Orsiro stents, 481 patients were randomly assigned to 3‐month DAPT and 491 to 12‐month DAPT. At 12 months, the target vessel failure, defined as a composite of cardiac death, target vessel–related myocardial infarction, or target vessel revascularization, occurred in 8 patients (1.7%) in the 3‐month DAPT group and in 14 patients (2.9%) in the 12‐month DAPT group (hazard ratio [HR], 0.58; 95% CI, 0.24–1.39; P=0.22). In whole population who were randomly assigned to receive 3‐month DAPT (n=1495), there was no significant difference in the target vessel failure between the Orsiro group and the everolimus‐eluting stent group (n=1014) (1.7% versus 1.8%; HR, 0.96; 95% CI, 0.41–2.22; P=0.92).

Conclusions

In patients receiving Orsiro stents, clinical outcomes at 1 year were similar between the 3‐month DAPT followed by P2Y12 inhibitor monotherapy and 12‐month DAPT strategies. With 3‐month DAPT, there was no significant difference in target vessel failure between Orsiro and everolimus‐eluting stents.

Registration

URL: https://www.clinicaltrials.gov; Unique identifier: NCT02079194.

Recent Advances in Manufacturing Innovative Stents

Cardiovascular diseases are the most distributed cause of death worldwide. Stenting of arteries as a percutaneous transluminal angioplasty procedure became a promising minimally invasive therapy based on re-opening narrowed arteries by stent insertion. In order to improve and optimize this method, many research groups are focusing on designing new or improving existent stents. Since the beginning of the stent development in 1986, starting with bare-metal stents (BMS), these devices have been continuously enhanced by applying new materials, developing stent coatings based on inorganic and organic compounds including drugs, nanoparticles or biological components such as genes and cells, as well as adapting stent designs with different fabrication technologies. Drug eluting stents (DES) have been developed to overcome the main shortcomings of BMS or coated stents. Coatings are mainly applied to control biocompatibility, degradation rate, protein adsorption, and allow adequate endothelialization in order to ensure better clinical outcome of BMS, reducing restenosis and thrombosis. As coating materials (i) organic polymers: polyurethanes, poly(ε-caprolactone), styrene-b-isobutylene-b-styrene, polyhydroxybutyrates, poly(lactide-co-glycolide), and phosphoryl choline; (ii) biological components: vascular endothelial growth factor (VEGF) and anti-CD34 antibody and (iii) inorganic coatings: noble metals, wide class of oxides, nitrides, silicide and carbide, hydroxyapatite, diamond-like carbon, and others are used. DES were developed to reduce the tissue hyperplasia and in-stent restenosis utilizing antiproliferative substances like paclitaxel, limus (siro-, zotaro-, evero-, bio-, amphi-, tacro-limus), ABT-578, tyrphostin AGL-2043, genes, etc. The innovative solutions aim at overcoming the main limitations of the stent technology, such as in-stent restenosis and stent thrombosis, while maintaining the prime requirements on biocompatibility, biodegradability, and mechanical behavior. This paper provides an overview of the existing stent types, their functionality, materials, and manufacturing conditions demonstrating the still huge potential for the development of promising stent solutions.

Endpoint selection for noninferiority percutaneous coronary intervention trials: a methodological description

Background:

The objective of this review is to provide a practical update on endpoint selection for noninferiority (NI) studies in percutaneous coronary intervention studies.

Methods:

A PubMed search was conducted for predefined terms to explore the use of NI designs and intrapatient comparisons to determine their current importance. Sample size calculations for the most frequently used endpoints with NI hypotheses were done to increase statistical awareness.

Results:

Reported NI trials, with the most frequently chosen clinical endpoint of major adverse cardiac events (MACE), had NI margins ranging from 1.66% to 5.00%, resulting in patient populations of 400–1500 per treatment group. Clinical study endpoints comprising of MACE complemented with rates of bleeding complications and stent thrombosis (ST) are suggested to conduct a statistically and clinically meaningful NI trial. Study designs with surrogate endpoints amenable to intrapatient randomizations, are a very attractive option to reduce the number of necessary patients by about half. Comparative clinical endpoint studies with MACE and ST/bleeding rates to study a shortened dual antiplatelet therapy (DAPT) in coronary stent trials are feasible, whereas ST as the sole primary endpoint is not useful.

Conclusions:

Expanded composite clinical endpoints (MACE complemented by ST and bleeding rates and intrapatient randomization for selected surrogate endpoints) may be suitable tools to meet future needs in device approval, recertification and reimbursement.

Ultrathin (60 μm), ultralong (≥40 mm) sirolimus-eluting stent: study of clinical and safety profiles among real-world patients

OBJECTIVE

Although thin-strut drug-eluting stents (DES) with a more flexible design are easily obtainable, data regarding using ultralong DES (≥40 mm) for long coronary lesions are limited in the literature. Therefore, the current study assessed the safety and efficacy of an ultralong (≥40 mm) and ultrathin (60 μm) biodegradable polymer-coated sirolimus-eluting stent (SES), Supralimus Grace, with a unique Long Dual Z-link (LDZ-link) design (Sahajanand Medical Technologies Pvt. Ltd., Surat, India) in real-world patients with long coronary lesions.

METHODS

The assigned stents were implanted in 684 patients. The primary endpoint was target lesion failure (TLF), which is a composite of cardiovascular death, target vessel myocardial infarction (MI), and target lesion revascularization (TLR), whereas periprocedural secondary endpoints included device failure (failure of stent delivery, change of stent, and stent fracture) and patient-oriented composite endpoint (POCE), which is a composite of all deaths, any MI, and any revascularization, and stent thrombosis (ST). These outcomes were analyzed at one-year follow-up and during the procedure.

RESULTS

The patients' mean age was 52.7±15.9 years; 537 (78.5%) were males. 626 (91.5%) patients suffered from acute coronary syndrome and 58 (8.5%) patients from chronic coronary syndrome (CSS). 989 lesions were removed. The mean numbers of lesions and stents implanted per patient were 1.3±0.2 mm and 1.4±0.3 mm, respectively. TLF occurred in 42 (6.1%) as a result of cardiac death, target vessel MI, and TLR in 9 (1.3%), 20 (2.9%), and 13 (1.9%) patients, respectively. POCE was observed in 131 patients (19.1%) at one-year follow-up, mainly in 63 (9.2%) patients because of any revascularization. Stent failure was seen in 21 patients (3.1%) as a result of delivery failure (2.2%), edge dissection (0.8%), and fracture (0.1%). Definite and probable ST were observed in 8 (1.1%) and 9 (1.3%) patients, respectively.

CONCLUSION

Ultralong (≥40 mm), ultrathin (60 μm) Supralimus Grace stent can be safely implanted in vessels having long and multiple lesions.

Two-year clinical outcome of all-comers treated with three highly dissimilar contemporary coronary drug-eluting stents in the randomised BIO-RESORT trial

AIMS

The aim of the study was to evaluate the two-year clinical outcome of all-comer trial participants who were treated with two very different thin-strut biodegradable polymer versus thin-strut durable polymer drug-eluting stents (DES). Prolonged clinical outcome after discontinuation of dual antiplatelet therapy is of particular interest, given the highly dissimilar polymer types, amount, distribution, and degradation speed of both biodegradable polymer DES.

METHODS AND RESULTS

The BIO-RESORT trial (NCT01674803) randomly assigned 3,514 patients to treatment with biodegradable polymer SYNERGY everolimus-eluting stents (EES) or Orsiro sirolimus-eluting stents (SES), or durable polymer Resolute Integrity zotarolimus-eluting stents (ZES). At two-year follow-up (available in 98.8%), the rate of the primary composite endpoint target vessel failure (TVF) was 8.3% in ZES versus 6.8% in EES (p=0.19) and 6.6% in SES (p=0.12). Landmark analyses at one year revealed differences between SES and ZES in the rates of target lesion revascularisation and target lesion failure (0.6% vs. 1.5%, p=0.04, and 1.1% vs. 2.4%, p=0.02, respectively) as well as other composite secondary endpoints that reached statistical significance.

CONCLUSIONS

At two-year follow-up, there was no significant between-DES difference in the rates of the primary endpoint. Landmark analyses provided a signal that the use of SES versus ZES might reduce the risk of repeat revascularisation after one-year follow-up.

Orsiro: ultrathin bioabsorbable polymer sirolimus-eluting stent

Recent stent developments aimed to reduce and eliminate the long-term inflammatory response include thinner struts, modifications to stent design and the development of bioresorbable polymers (BP). We aimed to summarize the main findings and to discuss the established and the potential benefits of the Orsiro BP sirolimus-eluting stents in everyday clinical use. We have reviewed the available evidence on the clinical performance of the Orsiro BP drug-eluting stents. Orsiro BP sirolimus-eluting stents is clinically proven and showed noninferiority against major drug-eluting stents and provides high safety and efficacy profile at long-term follow-up. Furthermore, it may be the preferred treatment option in specific subgroups as acute coronary syndrome, as shown in the BIOFLOW V trial.

High Bleeding Risk Patients Treated with Very Thin-Strut Biodegradable Polymer or Thin-Strut Durable Polymer Drug-Eluting Stents in the BIO-RESORT Trial

Purpose

Patients with high bleeding risk (HBR) who undergo percutaneous coronary intervention also have an increased risk of ischemic events and represent an overall high-risk population. The coating of durable polymer drug-eluting stents (DP-DES) may induce inflammation and delay arterial healing, which might be reduced by novel biodegradable polymer DES (BP-DES). We aimed to evaluate the safety and efficacy of treating HBR patients with very thin-strut BP-DES versus thin-strut DP-DES.

Methods

Participants in BIO-RESORT (NCT01674803), an investigator-initiated multicenter, randomized all-comers trial, were treated with very thin-strut BP-DES (Synergy or Orsiro) or thin-strut DP-DES (Resolute Integrity). For the present analysis, patients were classified following HBR criteria based on previous trials. The primary endpoint was target vessel failure: a composite of cardiac death, target vessel-related myocardial infarction, or target vessel revascularization at 1 year.

Results

Of all 3514 patients, 1009 (28.7%) had HBR. HBR patients were older (p < 0.001) and had more co-morbidities than non-HBR patients (p < 0.001). At 1-year follow-up, HBR patients had significantly higher rates of target vessel failure (6.7 vs. 4.2%, p = 0.003), cardiac death (1.9 vs. 0.4%, p < 0.001), and major bleeding (3.3 vs. 1.5%, p = 0.001). Of all 1009 HBR patients, 673 (66.7%) received BP-DES and 336 (33.3%) had DP-DES. The primary endpoint was met by 43/673 (6.5%) patients treated with BP-DES and 24/336 (7.3%) treated with DP-DES (HR 0.88 [95%CI 0.54–1.46], p = 0.63). There were no significant between-group differences in the most global patient-oriented clinical endpoint (9.7 vs. 10.5%, HR 0.92 [95%CI 0.61–1.39], p = 0.69) and other secondary endpoints.

Conclusions

At 1-year follow-up, very thin-strut BP-DES showed similar safety and efficacy for treating HBR patients as thin-strut DP-DES.

Electronic supplementary material

The online version of this article (10.1007/s10557-018-6823-9) contains supplementary material, which is available to authorized users.

Nobori-Biolimus-Eluting Stents versus Resolute Zotarolimus-Eluting Stents in Patients Undergoing Coronary Intervention: A Propensity Score Matching

PURPOSE

To compare the 1-year outcomes of a durable polymer Zotarolimus-eluting stent (ZES) versus a biodegradable polymer Biolimus-eluting stent (BES) in patients undergoing percutaneous coronary intervention.

MATERIALS AND METHODS

A total of 2083 patients from 2 different registries, 1125 treated with BES in NOBORI registry and 858 received ZES in CONSTANT registry were included in this study. Clinical outcomes were compared with the use of propensity score matching (PSM). The primary endpoint was a composite of major adverse cardiovascular and cerebrovascular events (MACCEs) including cardiac death, myocardial infarction, clinically driven target lesion revascularization and stroke. Secondary end points were individual components of MACCEs as well as the incidence of stent thrombosis at 1-year follow-up.

RESULTS

After PSM, 699 matched pairs of patients (n=1398) showed no significant difference between BES and ZES in the risk of composite MACCEs at 1 year (2.6% vs. 1.7%; p=0.36). Cardiac death was not statistically different between groups (0.7% vs. 0.4%, p=0.73). Target lesion revascularization rate was also similar between BES and ZES (1.1% vs. 0.7%, p=0.579). Non-Q wave myocardial infarction, as well as target-vessel revascularization rate, was similar between the two groups (0.14% for BES and 0.72% for ZES). Both stent types were excellent with no cases of stent thrombosis and rate of Q wave myocardial infarction reported during the follow-up period.

CONCLUSION

In this cohort of patients treated with BES or ZES, the rate of MACCEs at 1 year was low and significantly not different between both groups.

Very thin strut biodegradable polymer everolimus-eluting and sirolimus-eluting stents versus durable polymer zotarolimus-eluting stents in allcomers with coronary artery disease (BIO-RESORT): a three-arm, randomised, non-inferiority trial

BACKGROUND

In patients with coronary artery disease, treated with durable polymer-coated drug-eluting stents, the life-long presence of the polymer might delay arterial healing. Novel very thin strut biodegradable polymer stents, which leave only a bare metal stent after polymer resorption, might improve long-term outcome. We investigated in allcomers the safety and efficacy of three stents eluting either everolimus, sirolimus, or zotarolimus, often clinically used but never compared, of which the biodegradable polymer everolimus-eluting stent was never before assessed in allcomers.

METHODS

The large-scale, investigator-initiated, multicentre, assessor and patient blinded, three-arm, randomised, BIO-RESORT non-inferiority trial was done at four clinical sites in the Netherlands. All-comer patients were aged 18 years or older, capable of providing informed consent, and required a percutaneous coronary intervention with drug-eluting stent implantation according to clinical guidelines or the operators' judgment. Exclusion criteria were: participation in another randomised drug or device study before reaching the primary endpoint of that study; planned surgery necessitating interruption of dual antiplatelet therapy within the first 6 months; known intolerance to components of the investigational product or medication required; uncertainty about the adherence to follow-up procedures or an assumed life expectancy of less than 1 year; or known pregnancy. Web-based computer-generated allocation sequences randomly assigned patients (1:1:1) to treatment with very thin strut biodegradable polymer everolimus-eluting or sirolimus-eluting stents (which differ substantially in type, amount, distribution, and resorption speed of their respective coating), or thin strut durable polymer zotarolimus-eluting stents. The primary endpoint was a composite of safety (cardiac death or target vessel-related myocardial infarction) and efficacy (target vessel revascularisation) at 12 months of follow up with a very thin strut biodegradable polymer of either everolimus-eluting or sirolimus-eluting stents, compared with durable polymer zotarolimus-eluting stents, analysed by intention to treat (non-inferiority margin 3·5%). This trial was registered with ClinicalTrials.gov, number NCT01674803.

FINDINGS

From Dec 21, 2012, to Aug 24, 2015, 3514 patients were enrolled and analysed, of whom 2449 (70%) had acute coronary syndromes, which included 1073 (31%) ST-elevation myocardial infarctions. 12 month follow-up of 3490 (99%) patients (three lost to follow-up; 21 withdrawals) was available. The primary endpoint was met by 55 (5%) of 1172 patients assigned to everolimus-eluting stents, 55 (5%) of 1169 assigned to sirolimus-eluting stents and 63 (5%) of 1173 assigned to zotarolimus-eluting stents. Non-inferiority of the everolimus-eluting stents and sirolimus-eluting stents compared with zotarolimus-eluting stents was confirmed (both -0·7% absolute risk difference, 95% CI -2·4 to 1·1; upper limit of one sided 95% CI 0·8%, p_{non-inferiority}<0·0001). Definite stent thrombosis (defined by the Academic Research Consortium) occurred in four (0·3%) of 1172 patients who were allocated to everolimus-eluting stents, four (0·3%) of 1169 patients who were allocated to sirolimus-eluting stents, and three (0·3%) of 1173 patients who were allocated to zotarolimus-eluting stents (log-rank p=0·70 for both comparisons with zotarolimus-eluting stents).

INTERPRETATION

At 12 month follow-up, both very thin strut drug-eluting stents with dissimilar biodegradable polymer coatings (eluting either everolimus or sirolimus) were non-inferior to the durable polymer stent (eluting zotarolimus) in treating allcomers with a high proportion of patients with acute coronary syndromes. The absence of a loss of 1 year safety and efficacy with the use of these two biodegradable polymer-coated stents is a prerequisite before assessing their potential longer-term benefits.

FUNDING

Biotronik, Boston Scientific, and Medtronic.

Paclitaxel-coated balloon plus bare-metal stent for de-novo coronary artery disease: final 5-year results of a randomized prospective multicenter trial

BACKGROUND

The PERfECT Stent Study compared paclitaxel-coated balloon (PCB) angioplasty plus bare-metal stent (BMS) implantation with BMS alone in de-novo lesions in native coronary artery disease. Angiographic follow-up after 6 months showed the superiority of the additional PCB. We evaluated a potential late catch-up phenomenon with the use of PCB.

METHODS AND RESULTS

In the prospective, multicenter, single-blind, randomized PERfECT Stent trial, 120 patients were assigned to either PCB angioplasty plus BMS implantation or BMS alone. For BMS, the endothelial progenitor cell capturing stent was used. Dual antiplatelet therapy was recommended for 3 months. The clinical endpoint for 5-year follow-up was a composite of cardiac death, myocardial infarction attributed to the target vessel, or target lesion revascularization. The follow-up rate after 5 years was 97%. Baseline and procedural characteristics did not differ. At the 5-year follow-up, clinically driven target lesion revascularization was 23.2% in the BMS group versus 15% with PCB plus BMS (P=0.26). The clinical endpoint (major adverse cardiac event) was 30.4% with BMS and with 23.5% lower with PCB plus BMS. No definite or probable stent thrombosis was found in either group with a dual antiplatelet therapy for 3 months for the total period.

CONCLUSION

PCB angioplasty plus BMS was superior to BMS alone for the treatment of de-novo lesions. The combined clinical endpoint was lower with PCB plus BMS at 6 months and remained lower after 5 years. There was no late catch-up phenomenon (http://www.clinicaltrials.gov; NCT 00732953).

Biodegradable Airway Stents - Bench to Bedside: A Comprehensive Review

Airway stents are indicated to treat symptomatic narrowing or to close fistulas of the central airways. They are generally divided into two types: the silicone stents and the metallic stents. Unlike in malignancies, removability is a major objective of temporary stenting in benign conditions, which poses the challenge of a new rigid bronchoscopic procedure under general anesthesia and stent removal with all its attendant risks and costs. The concept of a biodegradable (BD) stent that could maintain the patency of an airway for a predetermined duration of time is very appealing. These BD stents would gradually degrade and eventually vanish from the airway once they are no longer needed. Such stents are currently an area of intense research. Another very promising concept of drug delivery with such stents is also a very exciting area of current research. The aim of this comprehensive review is to discuss all pertinent available literature on the use of BD materials in various clinical applications and to extensively review all animal and humans trials involving BD airway stents.

Zotarolimus-eluting durable-polymer-coated stent versus a biolimus-eluting biodegradable-polymer-coated stent in unselected patients undergoing percutaneous coronary intervention (SORT OUT VI): a randomised non-inferiority trial

BACKGROUND

New-generation drug-eluting coronary stents have reduced the risk of coronary events, especially in patients with complex disease or lesions. To what extent different stent platforms, polymers, and antiproliferative drugs affect outcomes, however, is unclear. We investigated the safety and efficacy of a third-generation stent by comparing a highly biocompatible durable-polymer-coated zotarolimus-eluting stent with a biodegradable-polymer-coated biolimus-eluting stent.

METHODS

This open-label, randomised, multicentre, non-inferiority trial was done at three sites across western Denmark. All patients who presented with stable coronary artery disease or acute coronary syndromes and at least one coronary artery lesion (more than 50% stenosis) from March, 2011, to August, 2012, were assessed for eligibility. Patients were randomly assigned in a 1:1 ratio to receive either the durable-polymer zotarolimus-eluting stent or the biodegradable-polymer biolimus-eluting stent. The primary endpoint was a composite of safety (cardiac death and myocardial infarction not clearly attributable to a non-target lesion) and efficacy (target-lesion revascularisation) at 12 months, analysed by intention to treat. The trial was powered to assess non-inferiority of durable-polymer zotarolimus-eluting stent compared with the biodegradable-polymer biolimus-eluting stent with a predetermined non-inferiority margin of 0·025. This trial is registered with ClinicalTrials.gov, number NCT01956448.

FINDINGS

Of 7103 screened, 1502 patients with 1883 lesions were assigned to receive the durable-polymer zotarolimus-eluting stent and 1497 patients with 1791 lesions to receive the biodegradable-polymer biolimus-eluting stent. 79 (5·3%) and 75 (5·0%) patients, respectively, met the primary endpoint (absolute risk difference 0·0025, upper limit of one-sided 95% CI 0·016%; p=0·004). The individual components of the primary endpoint did not differ significantly between stent types at 12 months.

INTERPRETATION

The durable-polymer-coated zotarolimus-eluting stent was non-inferior to the biodegradable-polymer-coated biolimus-eluting stent in unselected patients.

FUNDING

Medtronic Cardiovascular and Biosensors Interventional Technologies.

Strategies to direct the enrichment, expansion, and recruitment of regulatory cells for the treatment of disease

Disease and injury perturb the balance of processes associated with inflammation and tissue remodeling, resulting in positive feedback loops, exacerbation of disease and compromised tissue repair. Conversely, under homeostatic healthy conditions, these processes are tightly regulated through the expansion and/or recruitment of specific cell populations, promoting a balanced steady-state. Better understanding of these regulatory processes and recent advances in biomaterials and biotechnology have prompted strategies to utilize cells for the treatment and prevention of disease through regulation of inflammation and promotion of tissue repair. Herein, we describe how cells that regulate these processes can be increased in prevalence at a site of disease or injury. We review several relevant cell therapy approaches as well as new strategies for directing endogenous regulatory cells capable of promoting environmental homeostasis and even the establishment of a pro-regenerative micro-environment. Collectively, these examples may provide a blueprint for next-generation "medicine" that spurs the body's own cells to action and replaces conventional drugs.