This technique is known as Collagen Induced Technique (CIT). All this is a very complex process, but the principle is quite easy to understand.
In Microneedling we simply utilize the body’s self-healing mechanisms. It reacts to the intrusion of micro-needles like it would react to any other skin penetrating object. But the difference is the size of the object – the micro-needle. The intrusion of tiny surgical needles (provided they are professionally designed) is sensed by skin nerve receptors as an injury stimulus. But the needles are so fine and thin that tissue damage is unlikely.
The skin integrity actually stays intact. However, this “nerve-stimulus”, transported by electrical signals, triggers the cascade of the healing process.