Injection systems and methods of their use

A kit for injection of an injection agent into a tissue comprising:

• an injection system comprising:
• a syringe barrel defining a lumen between a proximal end and a distal end;
• a first sealing element moveably disposed within the lumen;
• a second sealing element moveably disposed within the lumen proximal to the first sealing element, wherein the first sealing element and the second sealing element form a seal with the lumen and define an injection chamber between them;
• a puncture element extending from a distal end of the first sealing element, the puncture element being in fluid communication with the injection chamber to deliver an injection agent from the injection chamber into a space in a tissue of a patient;
• a unidirectional stop disposed in the syringe barrel between the first sealing element and the second sealing element, the unidirectional stop being configured to:
• contact the first sealing element during pre-insertion of the puncture element into the tissue,
• prevent a proximal movement of the first sealing element past the unidirectional stop during delivery of the injection agent, and
• allow the second sealing element to pass through the unidirectional stop to contact the first sealing element after delivery of the injection agent;
• and
• a volume of the injection fluid comprising one or more injection agent formulations.