**7. Conclusions**

Photodynamic therapy is a recognized alternative used in successful cancer therapy, in a society when the clinicians are seeking new and efficient methods for saving people. There is no doubt that the long scientific efforts of photodynamic therapy will allow useful patient treatments in the future.

*The main benefits* of PDT are the following:

**a.** The patients can avoid surgery.

In our experimental approach, we have obtained from untreated skin biopsies a mean of

**Figure 23.** Primary keratinocytes isolated from normal human skin before (control) and after PDT with TPPS4 (viability

Primary keratinocytes were further cultivated until the culture could not be maintained. The proliferation capacity of primary keratinocytes extracted from PDT skin biopsies was signifi‐ cantly lower compared to control skin (Figure 23). Annexin-V and propidium iodide labelling of isolated keratinocytes after in vivo PDT compared to control keratinocytes yielded to the

The tested TPPS4 showed an effective *in vivo* destructive effect on keratinocytes in the patient

Photodynamic therapy is a recognized alternative used in successful cancer therapy, in a society when the clinicians are seeking new and efficient methods for saving people. There is

following values: control = 100 %; An-PI- = 10 %; An+PI- = 18 %; An+PI+ = 65 %.

with actinic keratosis doubled by a good clinical response (Figure 24).

**Figure 24.** The aspect of the skin with AK before PDT (left) and after PDT (right) with TPPS4

control skin, displaying as well a lower viability (Figure 23).

 keratinocytes/cm2 skin with a mean of 65% viability. After therapy from the same skin region and from the same surface isolated keratinocytes were less than half compared to the

2.8x106

276 Advances in Bioengineering

and proliferative capacity)

**7. Conclusions**


*Side effects, limitations* could be registered, especially for photosensitivity or sensitivity to light, the pain of PDT, which is usually mild to moderate, easily controlled with some drugs.

However, there are *many problems* for the clinical application of existing photosensitzers.

